HYBRID MULTIFERROIC CALAMITIC LIQUID CRYSTAL SOLAR CELL WITH AMYL-4-(4-ETHOXYPHENOXY)PHENYL CARBONATE ELECTROLYTE

Abstract

Abstract HYBRID MULTIFERROIC CALAMITIC LIQUID CRYSTAL SOLAR CELL WITH AMYL-4-(4-ETHOXYPHENOXY)PHENYL CARBONATE ELECTROLYTE The present invention provides hybrid multiferroic calamitic liquid crystal solar cell by incorporating lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate for improving power conversion efficiency of the solar cell. Hybrid multiferroic calamitic liquid crystal (HMLC) solar cell comprises a first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode 101, a second thin layer of light absorbing inorganic sensitizer 103; wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode, a third layer of lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate is as a ferroelectric calamitic liquid crystal electrolyte at room temperature 104 applied between the light absorbing electrode and a light reflecting electrode and a fourth layer of reflective platinum deposited FTO glass-electrode 105 configured to act as the light reflecting electrode. The components between the two electrodes (metal oxide, metal) act as multiferroic solid-liquid crystal composite. The direction of movement of electrons between two electrodes can be altered through the polarization direction of multiferroic solid-liquid crystal composite. It means the anode and the cathode can be altered within hybrid multiferroic calamitic liquid crystal solar cell through the change in the direction of ferroelectric polarization between two electrodes (metal oxide, metal). ABSTRACT (Fig.)

Specification

Description:HYBRID MULTIFERROIC CALAMITIC LIQUID CRYSTAL SOLAR CELL WITH AMYL-4-(4-ETHOXYPHENOXY)PHENYL CARBONATE ELECTROLYTE
FIELD OF THE INVENTION
[0001] The embodiments herein generally relate to multiferroic calamitic liquid crystal photovoltaic solar cell or tunnel diode. In particular, the invention relates to incorporation of amyl-4-(4-ethoxyphenoxy)phenyl carbonate electrolyte in the solar cell for improving power conversion efficiency of a hybrid multiferroic calamitic liquid crystal solar cell beyond SHOCKLEY-QUEISSER power conversion efficiency limit (33 %) as well as above one hundred (100) % power conversion efficiency value in solar cells for the first time since the discovery of solar cells.

[0002] Renewable energy is the key to solve future energy crisis as green energy. In that solar energy is a leading resource. Currently, there are three different generations of solar cell technologies that have been established. The fabrication cost, power conversion efficiency and stability of solar cell are crucial factors in solar cell technology. The first generation solar cells are crystalline silicon (Si) solar cells, second generation solar cells are thin film amorphous Si solar cells, cadmium telluride (CdTe) solar cells, copper indium gallium selenide (CIGS) solar cells and third generation solar cells are dye sensitized solar cells (DSSCs), quantum dot solar cells (QDSCs), organic p-n bulk hetero junction (BHJ) solar cells, organic tandem solar cells, perovskite solar cells and solid-state multiferroic (ferroelectric) (ME or FE) solar cells and hybrid ferroelectric (multiferroic) liquid crystal solar cells. Hybrid multiferroic liquid crystal solar cell invented by Indian physical chemist Ananda Rama Krishnan SELVARAJ on 25.03.2015 [(US. Pat. No. US2022/11462364 B2 (2022), JP. Pat. No. JP2023/7410520 (2023), UK. Pat. No. UK2022/GB2591561 (2022), IN. Pat. No. IN2019/313063 (2019), AUS. Pat. Pub. No. AU-A-2018425918 (2021), WIPO:PCT. Pub. No. WO 2019/229514 A1].
[0003] The maximum power conversion efficiency (PCE) value of first generation single crystalline Si solar cell is 27.6 %, the PCE value of second generation gallium arsenide solar cell is 30.8 %, the PCE value of third generation perovskite solar cell is 26.7 %, the PCE value of third generation Quantum dot solar cell is 19.1 % and the PCE value of third generation Dye sensitized solar cell is 13 % and the PCE of third generation organic p-n junction solar cell is 19.2 % and the PCE value of third generation solid-state ferroelectric solar cells is 8.1 % and the PCE value of hybrid ferroelectric (multiferroic) discotic liquid crystal (HFLC) solar cell is 24.5 % and the PCE value of hybrid multiferroic calamitic (rod-shaped) liquid crystal solar cell is 8.55 % and the PCE value of hybrid multiferroic calamitic liquid crystal solar cell with pure chiral calamitic liquid crystal (pure 5CB star) as electrolyte is above SHOCKLEY-QUEISSER limit as well as above one hundred (100) % .
[0004] The power conversion efficiency (PCE) (η) of solar cell is defined by short-circuit photo-current (Jsc), open-circuit voltage (Voc), fill factor (FF) and light intensity of illumination. The power conversion efficiency (η) = [Jsc) (mA/sq.cm) * (Voc) (V) * FF (value from 0 to 1)] / Incident light intensity (100 mW/sq.cm). Further, the fill factor (FF) of solar cell is estimated as FF = Pmax [Vmax (V) * Imax (A)] / [Jsc (A) * Voc (V)] where Pmax is power maximum, Vmax is the voltage maximum, and Imax is the current maximum. The physical meaning of power conversion efficiency (PCE) value in solar cell is based on the conversion of photons from solar illumination (solar energy) to electron (exciton: electron-hole pair) and subsequent movement of electrons and holes towards the opposite electrodes within solar cell and their collection by the opposite electrodes. The solar cell will have one hundred (100) % power conversion efficiency if it fulfills the following conditions 1. Complete conversion of all the absorbed photons by the solar cell to electrons (exciton: electron-hole pairs), 2. Complete dissociation of excitons into electrons and holes, 3. Complete collection of electrons and holes by the opposite electrodes within the solar cell without recombination or any other process. The recombination of excited electrons is common in all p-n junction solar cells therefore PCE value of p-n junction solar cells is always less than one hundred (100) % and this is the basis for the formulism of SHOCKLEY-QUEISSER (SQ) PCE limit (30 %) in 1961. Furthermore, achieving PCE value above one hundred (100) % in solar cell is the evidence for the multi-excitons formation and there is no or less electron recombination process in such solar cell, and these cannot be achieved together in p-n junction solar cells. It is possible with multiferroic liquid crystal solar cells.
[0005] The quantum efficiency (QE) of the solar cell is the ratio between the charge carriers generated (collected) by the solar cell and the number of photons absorbed by the solar cell (QE = charge carriers / absorbed photons). The one hundred (100) % QE value of the solar cell indicates that the 100 % power conversion efficiency value of the solar cell at particular wavelength of solar spectrum. The less QE value of solar cell is due to the reflection and transmission of photons and low diffusion length of charge carriers and recombination of charge carriers. In typical solar cells, the absorption of photons below or above the band gap value of semiconductors is not possible. In multiferroic solar cells, the complete absorption of solar energy spectrum is possible. Further there is no charge recombination effect in multiferroic solar cells because the charge separation in ferroelectric solar cells occurs through the polarization value of multiferroic system within the solar cell and the electron transport is ballistic nature. Therefore, it is possible to reach 100 % QE or more with multiple charge carriers formation in multiferroic liquid crystal solar cells. The external quantum efficiency (EQE) of the solar cell is the ratio between generated electrons by the solar cell and absorbed photons by the solar cell (EQE = electrons / absorbed photons) and the EQE always includes optical losses such as reflection and transmission of absorbed photons and recombination of charge carriers. The internal quantum efficiency (IQE) of the solar cell does not includes optical losses and recombination losses therefore IQE will give exact quantum efficiency of the solar cell (IQE = electrons / (reflected photons + transmitted photons) - absorbed photons). In typical p-n junction solar cells, optical losses and recombination losses are common therefore EQE is considered as exact QE of p-n junction solar cell than IQE and the value of IQE is always higher than EQE around (10 to 20 %) in such solar cells. In multiferroic liquid crystal solar cell, the exact quantum efficiency value of the solar cell can be IQE because there is no recombination loss in the multiferroic liquid crystal solar cell.
[0006] Regarding, the SHOCKLEY-QUEISSER (SQ) theoretical power conversion efficiency limit, it was proposed for p-n single junction solar cells with single band gap materials by William SHOCKLEY and Hans-Joachim QUEISSER in 1961. The maximum PCE value of p-n single junction solar cells is 30 % with a semiconductor having 1.1 eV as band gap as per the SQ PCE limit. Therefore, achieving PCE value more than SQ limit in single p-n junction solar cells is not possible (W. SHOCKLEY, H.J. QUEISSER, J. Appl. Phys. 32:3, 510-519, 1961). The basis of SQ limit is the recombination mechanism of excited electrons in p-n junction solar cells and it is also known as detailed balance limit of PCE of solar cells.
[0007] The possible ways to overcome SHOCKLEY-QUEISSER PCE limit are tandem solar cells, multiferroic (MF) [ferroelectric (FE)] solar cells, hybrid multiferroic liquid crystal solar cells, multi band solar cells and thermo photovoltaics through formations of hot carriers (excited electrons with excess energy), multiple exciton generation (characteristic feature of multiferroic materials) from exciton fission mechanisms. Moreover, multiferroic liquid crystal solar cells are different from p-n junction solar cells by the charge separation process. As mentioned earlier, in multiferroic solar cells the charge separation occurs by the polarization value across the multiferroic material in solar cell and in p-n junction solar cells the charge separation occurs by the free energy difference (ΔG) between p-type and n-type materials.
[0008] The materials with non-centrosymmetry are ferroelectrics. Electron tunneling is a characteristic feature of ferroelectric materials. It means that potential energy barrier free electron transitions. In this quantum mechanical phenomenon, the wave nature of electron can be realized in both sides of potential energy barrier during electron tunneling process. So far, such electron tunneling phenomenon has been reported in nanometer scale thickness of solid-state ferroelectric films or layers. Further, ferroelectrics are superconductors at zero resistance, and they have various applications in that one of them is photoferroelectrics. Photoferroelectrics phenomenon is the effect of non-equilibrium electron conductivity, it is the effect of photo excited electron mobility on birefringence of ferroelectric and electro optical crystals or in simple, it is a photorefractive effect. The electron transport mechanism in photoferroelectrics or photo-multiferroics (ferroelectrics, ferromagnetic, ferroelastics) under illumination is understood as "bulk-photovoltaic effect" or "anomalous (no logic) photovoltaic effect" so far. For a longer time, solar energy conversion is known in homogeneous photo-ferroelectrics and the solar energy conversion is shown in heterogenous solid-liquid crystal multiferroic composite in 2018. Ananda Rama Krishnan SELVARAJ [US. Pat. No. US2022/11462364 B2 (2022), JP. Pat. No. JP2023/7410520 (2023), UK. Pat. No. UK2022/GB2591561 (2022), IN. Pat. No. IN2019/313063 (2019), AUS. Pat. Pub. No. AU-A-2018425918 (2021), WIPO:PCT. Pub. No. WO 2019/229514 A1 & IN. Pat. Appl. 202441051265 (2024); UK. Pat. Appl. 2410382.2 (2024]. The charge separation in ferroelectric or multiferroic solar cells occurs through the internal polarization value across the multiferroic materials and it creates "bulk photovoltaic effect" or "anomalous photovoltaic effect." In bulk photovoltaic effect or anomalous photovoltaic effect, open-circuit photovoltage of ferroelectric or multiferroic solar cells can be beyond the band gap (Eg) difference of semiconductors. Furthermore, the bulk photovoltaic effect or anomalous photovoltaic effect is the violation of Boltzmann principle of detailed balance. As per the principle of detailed balance, in kinetic process (elementary reactions) at equilibrium each elementary process is in equilibrium with its reverse process and such a reverse process does not occur in bulk-photovoltaic effect or anomalous photovoltaic effect. Therefore, there is no recombination of charge carriers in ferroelectric or multiferroic solar cells.
[0009] The bulk photovoltaic effect or anomalous photovoltaic effect of ferroelectrics has been explained by two mechanisms namely, ballistic and shift mechanisms. In ballistic mechanism, non-equilibrium electrons or hot carriers reach the top of the conduction band with asymmetric momentum (excess kinetic energy in different directions) then reach the bottom of the band through electron mean path I0. The other mechanism is shift mechanism and it is quantum mechanical in nature and it considers non-diagonal elements of electron density matrix, and it is not based on the movement of electrons rather it is based on the shift (R) of charge carrier (e-) (sudden change in the path of charge carrier transport) in real space from one band to another band through inter band transition and the electron mean free path I0 is material dependent and it is a specific behavior of each material. V.M. Fridkin [V.M. Fridkin, Photoferroelectrics, Springer-Verlag, Berlin (1979)]
[0010] Three distinct types of molecules are able to form liquid crystal states through the rigid aromatic part and flexible alkyl or alkoxy chain parts. They are calamitic (rod shaped) molecules, discotic (disc shaped) molecules and bent-core (banana shaped) molecules. They are able to behave as one dimensional organic semiconductor or organic quantum dots or quantum wire depending on the number of monomer units stacked and oriented together in same direction because of 'π' electron stacking interactions between their aromatic core parts. Such stacking interactions are high in disc shaped molecules and bent-core molecules, and it results columnar and polar smectic liquid crystal states, respectively. The stacking interactions are less in calamitic or rod-shaped liquid crystals. Liquid crystal materials have potential to act as organic redox mediums.
[0011] In photo excitation, inorganic sensitizer forms electron-hole pairs and organic sensitizer forms Frenkel exciton (bound state of electron-hole) within solar cells under the solar illumination. Absorption of suitable wavelength photon results in separation of electron and hole in inorganic sensitizers. The organic sensitizer's "Frenkel exciton" needs an additional energy to separate into electron and hole pairs because of their larger electronic band gap value and it is higher than optical photon absorption edge of solar spectrum.
[0012] Phonons are the vibrational particles of solid state materials, and they are responsible for their low-energy excitation spectrum of solids, and they are not conserved, and they are like bosons, and they have integer spin values, and they are massless particles. The energy of the phonon (E) is E = (hω / 2) and E depends on the angular vibrational frequency value (ω), especially their energy is more depends on the symmetry of the crystal lattice of solids. They are classified as acoustic phonon and optical phonon. In acoustic phonon, positive and negative ions swing in same direction and in optical phonon, positive and negative ions swing in opposite direction (charge separation). As phonons, phasons are the vibrational particles of liquid crystal lattices, and they are responsible for the low energy excitation spectrum of liquid crystals, and they are massless particles. The rotational movement of molecules is high in liquid crystals, and it is continous, and it will reflect in the excitation spectrum of phasons in comparison with low energy excitation spectrum of phonons in solids. The rotational movement induced collision between phasons is high and it results in production of more phasons in liquid crystalline state by chain reaction and such collisions between the phonons in solid state materials are nil or not so high. The energy transfer from phonon to electron occurs in-plane mode (parallel) and the energy transfer from phason to electron occurs in perpendicular mode. The energy transfer from phason to electron is more obvious than the energy transfer from phonon to electron.
[0013] In chiral liquid crystals, for example during the phase transition from SmA liquid crystal state (achiral, non-tilted layer structure) to SmC* liquid crystal state (chiral, helical layer structure), soft mode and GOLDSTONE mode occur. Breaking the symmetry of SmA liquid crystal state and transforms it into SmC* liquid crystal state with reduced symmetry occurs at "soft mode" or symmetry breaking mode. The broken symmetry of SmA can be restored in SmC* liquid crystal state and it is "GOLDSTONE mode" or symmetry restoring mode. The phase transition in ferroelectric liquid crystals occurs by the inter band phason and electron interactions (couplings between phasons and electrons results in energy transfer promoted electron transitions). The excitation spectrum of SmC* liquid crystal state at GOLDSTONE mode (helical chiral liquid crystal state) is a gapless excitation or low energy excitation of phasons. In specific, the broken continuous symmetry of chiral nematic liquid crystal state can be restored in the isotropic liquid state of ferroelectric liquid crystals, and it is GOLDSTONE mode thus the symmetry of chiral nematic state is restored in isotropic liquid state. It means chiral isotropic liquid can be realized. It is a hydrodynamic mode. The excitations at GOLDSTONE mode are coherent and long-lived excitations though the collisions between the phasons are short-lived. The GOLDSTONE mode excitation spectrum occurs at zero-frequency. In principle, at zero-frequency there are no vibrational motions in the solid state molecules. In liquid crystals, there is a continuous non-stop rotational motion exists even at zero frequency, and it may be responsible for restoring the broken symmetry of "soft mode" at GOLDSTONE mode [I. MUSEVIC. et al, The physics of ferroelectric and antiferroelectric liquid crystals, World Scientific, New Jersey (1999)]. In this invention GOLDSTONE mode of is realized in chiral (ferroelectric) calamitic liquid crystal.
[0014] Liquid crystals are the electro-responsive soft materials. They change their macroscopic orientation upon application external electric field (E) to control the transmission of light. Usually, chiral dopants are added to liquid crystals to create macroscopic polarization and for the growth of helical superstructures from hundreds to thousands of nanometer length scales to retain helical orientation of liquid crystal molecules. The pitch values of such macromolecular helical super structures of liquid crystals are controlled by the concentration of chiral dopants and the different pitch values of helical superstructures determine their optical absorption, reflection, and transmission spectrum of such liquid crystal composites. The property of chiral dopant added liquid crystal composite is completely different from the property of pure liquid crystal and this kind of property makes them potential materials for cholesteric displays with rewritable color memory functions and quick color modulations and achieving these two functions in display liquid crystal materials is rare. The degree of coupling between electric field and liquid crystal molecules is crucial for their remarkable unusual behavior of such liquid crystal composites under electric field.
[0015] Applying external magnetic or DC electric field on ferroelectric liquid crystals (helical chiral liquid crystals) creates perturbations and it will distort their smooth helical structure to distorted soliton like structure (elongated helical structure). In a helical structure of chiral liquid crystals uniformly aligned dipoles of molecules are separated by  (180) domain walls. If the external electric or magnetic fields are applied on the ferroelectric liquid crystals, the distance between the domain walls will change and become narrow. It will give ultimately different soliton like helical structure of ferroelectric liquid crystals. The influence of external magnetic field on distortion of helical structure is two times higher than the influence of external DC electric field. The modified ferroelectric domain structures and the distance between the domain walls by the external fields have significant impact on open-circuit voltage created across the photo-ferroelectric liquid crystals and it will contribute to the "bulk photovoltaic effect or anomalous photovoltaic effect" of ferroelectric liquid crystals or multiferroic liquid crystals [I. MUSEVIC. et al, The physics of ferroelectric and antiferroelectric liquid crystals, World Scientific, New Jersey (1999)].
[0016] Avalanche process occurs in solid state photodetectors (Avalanche diode) through impact ionization (charge multiplications results high in short-circuit current) at finite non-zero bias potential. However, it is not realized in conventional solid state semiconductor devices under short-circuit conditions so far.
[0017] Singlet exciton fission is a spin-allowed photo-physical process, and it is a multi-exciton generation (MEG) process. In this process, singlet exciton with excess energy undergoes photo-fission process and forms two triplet excitons having half of its energy. The excited singlet exciton (S1) with excess of energy interacts with neighboring chromophore in ground state (S0) and forms two (T1) triplets excitons and these triplet excitons dissociate into electron and hole at the electrodes (S0 +S1  2 T1) and triplet excitons formations have contribution to the high short-circuit current values of photovoltaic devices and two electrons are involved in this singlet fission process. As per thermodynamics, the larger free energy difference between two triplet states and excited singlet state favors the singlet fission process GSF = 2 E (T1) - E (S1). Singlet fission occurs as intramolecular singlet fission and intermolecular singlet fission. In the former, it occurs between chromophores of the same molecule and in the latter, it occurs between chromophores of neighboring molecules. In case of multiple triplet excitons formations, the singlet exciton with excess of energy (S1) interacts with multiple neighboring chromophores (S0) in the ground state. The number of neighboring chromophores (S0) interactions with excess energized excited singlet state (S1) decides the number of triplet excitons formation in this singlet exciton fission process. However, the larger free energy difference between multiple triplet excitons and excited singlet exciton favors singlet exciton fission process and multiple electrons will be involved in this singlet exciton fission process.
[0018] Second-Harmonic-Generation (SHG) or frequency doubling occurs in ferroelectric or multiferroic non-linear compounds. In this phenomenon two photons of the same energy while interacting through non-linear material. They will combine together and will form a new single photon with double of its energy. In a same high energy photon while interacting through non-linear material, it can form two new photons with half of its energy. As per the frequency doubling, the wavelength of the incident light can be altered after passing it through the optically transparent ferroelectric or multiferroic materials. It means that the incident photon energy can be higher or lower by passing through ferroelectric or multiferroic liquid crystal materials (like stokes and anti-stokes lines). In such a way high energy exciton can be formed from high band gap (more than 3 eV) ferroelectric or multiferroic liquid crystal materials.
[0019] Materials with negative birefringence, negative dielectric permittivity, negative dielectric permeability, and negative refractive index are called metamaterials. They have various applications because of their tunable optic, electric and magnetic properties. The absorption of wide wavelength optical photons is possible in photovoltaic cells through metamaterials.
[0020] The chiral nematic liquid crystal state is the twisted single helical superstructure, and it is a potential material for display and various applications. The blue phase liquid crystal state is the twisted double helical superstructure with three dimensional (3D) periodic cubic lattices. The blue phase liquid crystal state occurs between chiral nematic liquid crystal state and isotropic liquid state and the blue phase liquid crystal state is optically isotropic (dark texture) and they will reflect selective wavelength of light. They have several distinctive features such as sub-millisecond response time, wide viewing angle and KERR-effect (change in refractive index in response to applied electric field). In specific, they are next generation display materials.
[0021] Electromagnons are known in solid-state multiferroics which are the combination of magnetic spin waves and crystal lattice vibrations of optical phonons, and it facilitates various applications of solid-state multiferroics. In hybrid multiferroic liquid crystal solar cells, the term "Electromagson" is introduced here which are the combinations of magnetic spin waves of liquid crystals and vibrations of optical phasons of liquid crystal lattices. It is a "quasiparticle." It is realized in this invention. The impact of electromagsons is shown in the performance of hybrid multiferroic calamitic liquid crystal solar cells and it has various other modern applications. Moreover, electromagsons or electromagnasons is a basic hypothetical quasiparticle for the most advanced phenomenon "Quantum Brain (QB)."
[0022] The present invention addresses the phenomena discussed earlier in this context.
[0023] Ananda Rama Krishnan SELVARAJ discovered the hybrid ferroelectric discotic liquid crystal (HFLC) solar cells using a lyotropic ferroelectric discotic liquid crystal redox medium and he achieved a PCE value of 24.5 % in HFLC solar cells as of now. [(US. Pat. No. US2022/11462364 B2 (2022), JP. Pat. No. JP2023/7410520 (2023), UK. Pat. No. UK2022/GB2591561 (2022), IN. Pat. No. IN2019/313063 (2019), AUS. Pat. Pub. No. AU-A-2018425918 (2021), WIPO:PCT. Pub. No. WO 2019/229514 A1]. In the structure of hybrid ferroelectric discotic liquid crystal (HFLC) solar cells, the first layer was optically transparent inorganic n-type titania semiconductor (TiO2) layer deposited on conductive FTO glass electrode with a thickness in few microns and the second layer was the light absorbing inorganic sensitizer molecules with a thickness of Angstrom to nanometers. Platinum deposited FTO glass is the other electrode (light reflecting layer). The lyotropic ferroelectric discotic liquid crystal redox was applied between the light absorbing and light reflecting electrodes in a sandwich type solar cell structure and the structure of hybrid ferroelectric discotic liquid crystal solar cell is metal-oxide/solid-liquid crystal ferroelectric composite/metal. In 2024, Ananda Rama Krishnan SELVARAJ reported hybrid multiferroic calamitic liquid crystal solar cell using lyotropic achiral calamitic liquid crystal (5CB) electrolyte and he achieved PCE value of 8.55 %. [IND. Pat. Appl. 202441051265 (2024), UK. Pat. Appl. GB2410382.2 (2024)]. Further in 2024, Ananda Rama Krishnan SELVARAJ reported hybrid multiferroic calamitic liquid crystal solar cell with power conversion efficiency value above SHOCKLEY-QUEISSER limit as well as above one hundred (100) % using pure chiral calamitic liquid crystal (5CB star) electrolyte. [IND. Pat. Appl. 202441081731 (2024), UK. Pat. Appl. GB2415881.8 (2024), US. Pat. Appl.18929670 (2024)]
[0024] The general structure of the solid state multiferroic or ferroelectric solar cell is metal/ferroelectrics (or) multiferroics/metal and the multiferroic or ferroelectric solar cells are not p-n junction solar cells. The specific feature of multiferroic solar cell is hysteretic behavior of photovoltaic-current and it means that the direction of flow (movement) of electrons between the electrodes can be altered by external fields through switching the direction of polarization of ferroelectrics or multiferroics either in  up or  down directions. V.M. FRIDKIN reported ferroelectric solar cells with photo-ferroelectric crystals. The ferroelectric solar cells have small short-circuit (Jsc) current value because of the larger electron band-gap values of photo-ferroelectric materials. Therefore, the PCE value of multiferroic or ferroelectric solar cells has not so high in the last forty five years of research [V.M. FRIDKIN, Photoferroelectrics, Springer-Verlag, Berlin (1979)]. In 2012, R. NECHACHE, et al. [US. Pat. No. US2012/0017976 A1 (2012)] reported solid state ferroelectric (FE) or multiferroic (MF) (ITO/BFCO/Nb-doped SrTiO3(001) solar cells with PCE value of 8.1 %, open circuit photo voltage of 0.84 V and short circuit photocurrent value of 20.6 mA/sq.cm. In 2018, Ananda Rama Krishnan SELVARAJ invented the hybrid ferroelectric discotic liquid crystal (HFLC) solar cell (FTO/TiO2/inorganic sensitizer (N719)/lyotropic ferroelectric discotic liquid crystal redox/Pt) with PCE value of 24.5 %, 2.1 V open-circuit (Voc) value as anomalous photovoltage. [US. Pat. No. US2022/11462364 B2 (2022), JP. Pat. No. JP2023/7410520 (2023), UK. Pat. No. UK2022/GB2591561 (2022), IN. Pat. No. IN2019/313063 (2019), AUS. Pat. Pub. No. AU-A-2018425918 (2021), WIPO:PCT. Pub. No. WO 2019/229514A1)]. Jonathan E. SPANIER, et al. [US. Pat. No. US2021/10903378 B2 (2021)] reported BaTiO3 (BTO) based solid-state multiferroic solar cell with 4.8 % of PCE using specific electrodes with particular arrangements and they claimed it as bulk photovoltaic effect (BPVE). In the nanoscale carrier (electron/holes) multiplication, hot carriers formation in BTO under illumination was discussed. Yeseul YUN, et al. (Yeseul YUN, et.al. Science Advances, 7, eabe4206, 2021) reported a solid state sandwich type of solar cell using ferroelectric BaTiO3 and paraelectrics SrTiO3 and CaTiO3 superlattice with enhanced photocurrent 103 times under the illumination of particular laser wavelength and authors suggested that the reported semiconductors composite can be used to overcome Shockley-Queisser PCE limit under air mass 1.5 illumination. In 2024, Ananda Rama Krishnan SELVARAJ reported [IND. Pat. Appl. No.202441051265 (2024); UK Pat. Appl. No. GB2410382.2 (2024)] hybrid multiferroic calamitic (rod-shaped) liquid crystal solar cell (FTO/TiO2/inorganic sensitizer (N719)/calamitic liquid crystal electrolyte/Pt; metal oxide / solid-liquid crystal multiferroic composite / metal) with 8.5 % PCE. In 2024, Ananda Rama Krishnan SELVARAJ reported hybrid multiferroic calamitic liquid crystal solar cell (FTO/TiO2/inorganic sensitizer (N719)/pure chiral calamitic liquid crystal electrolyte/Pt; metal oxide / solid-liquid crystal multiferroic composite / metal) with PCE value above SHOCKLEY-QUEISSER limit (30 %) as well as above one hundred (100) % using pure chiral calamitic liquid crystal (5CB star) as electrolyte. [IND. Pat. Appl. 202441081731 (2024), UK. Pat. Appl. GB2415881.8 (2024), US. Pat. Appl.18929670 (2024)]
[0025] In solid state multiferroic solar cells, a specific thickness (d) of homogeneous multiferroic materials generates steady-state-photocurrent under the continuous illumination of light and it depends on intensity and polarity of light. In hybrid multiferroic liquid crystal (HMLC) solar cells, a specific thickness of solid layers with liquid crystal as a charge transfer composite generates the steady-state-photocurrent under the continuous illumination of light. In open-circuit condition, photocurrent (Jpv) generates the photovoltage (Voc). Voc = [Jpv / (d + pv) ] * d, where d and pv are dark and photoconductivity of the multiferroic material, respectively. The photovoltaic field (Epv) can be defined as Epv = Jpv / pv , where pv = eI0(ℏ)-1 (µ) (e: electronic charge, I0: incident light intensity, : absorption coefficient of multiferroic material, : quantum yield of multiferroic material, ℏ: incident photon energy, µ, : mobility and lifetime of photocarriers. The bulk photovoltaic current (tensor value) is defined as Jpvi = gijlejelI0 (gijl: third rank piezoelectric tensor, ej, el: components of light polarization vectors). In an oriented multiferroic material this equation can be as Jpv = gI0, Epv = (g / (µ)pv) (ℏ/e). If the photoconductivity is much larger than the dark conductivity of the multiferroic materials (pv >> d), the photovoltaic field of multiferroics (Epv) will not change with light intensity (I0). At the same time, the photocurrent (Jpv) of multiferroic material will scale up linearly with light intensity (I0) as follows Jpv = eI0(ℏ)-1 ex l0 (ex: photoexcitation asymmetry parameter, l0 : ge-1I0ℏ(ex)-1. Thus, the power conversion efficiency of multiferroic solar cells () is related to piezoelectric (g) and photovoltaic electric field (Epv) values [V.M. FRIDKIN, Photoferroelectrics, Springer-Verlag, Berlin (1979)].
[0026] Regarding room temperature lyotropic ferroelectric liquid crystals redox mediums, the lyotropic ferroelectric discotic redox medium based hybrid ferroelectric discotic liquid crystal solar cell (metal oxide/solid-liquid crystal multiferroic composite/metal) was patented with 24.5 % PCE in 2018. Ananda Rama Krishnan SELVARAJ [US. Pat. No. US2022/11462364 B2 (2022), JP. Pat. No. JP2023/7410520 (2023), UK. Pat. No. UK2022/GB2591561 (2022), IN. Pat. No. IN2019/313063 (2019), AUS. Pat. Pub. No. AU-A-2018425918 (2021), WIPO:PCT. Pub. No. WO 2019/229514 A1)]. Using achiral calamitic liquid crystal redox medium, hybrid multiferroic calamitic liquid crystal solar cell (metal oxide/solid-liquid crystal multiferroic composite/metal) with 8.55 % PCE value achieved in 2024. Ananda Rama Krishnan SELVARAJ [IN. Pat. Appl. No. 202441051265/2024; UK. Pat. Appl. No. GB2410382.2/2024]. Using pure chiral calamitic (rod-shaped) ferroelectric liquid crystal (5CB star) as electrolyte in hybrid multiferroic calamitic liquid crystal (HMLC) solar cells, the PCE value above SHOCKLEY-QUEISSER limit (30 %) as well as above 100 % was achieved in 2024. Ananda Rama Krishnan SELVARAJ [IND. Pat. Appl. 202441081731 (2024), UK. Pat. Appl. GB2415881.8 (2024), US. Pat. Appl.18929670 (2024)]. In this invention, the photovoltaic performances of hybrid multiferroic calamitic liquid crystal solar cells with lyotropic liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate is reported. The results of hybrid multiferroic liquid crystal solar cells suggest that the open-circuit voltage (Voc) of HMLC solar cells is directly proportional to polarization value and photoactive area of multiferroic liquid crystal composite in HMLC solar cells as Voc  PA, where P is polarization of multiferroic liquid crystal composite and A is photoactive area of HMLC solar cells. Moreover, the electron transport in HMLC solar cell is ballistic (do not scatter inelastically) in nature and it is not as diffusive transfer of electron like in other type of solar cells. The time scale of electron transport in HMLC solar cell may be in picosecond or less and the time scale of electron transfer in HMLC solar cell needs to be investigated. Furthermore, the photovoltaic performances of hybrid multiferroic calamitic liquid crystal solar cells under dark condition are comparable with photovoltaic performances under solar illumination and it might be due to increased dark conductivity of electrolyte within the hybrid multiferroic liquid crystal solar cells. In typical p-n junction solar cells under dark condition there is no current at zero volt potential because there is no dark conductivity. Further, dark conductivity term is not in the definition of short-circuit current of p-n junction solar cells. In this invention, at zero volt potential under dark condition, a huge short-circuit current was found and it can be termed as "dark current," and the dark conductivity is part of the definition of short-circuit current value of multiferroic or ferroelectric solar cells. Furthermore, under dark condition hysteretic behavior is found in current-voltage measurements of hybrid multiferroic calamitic liquid crystal solar cells.
[0027] The generation of electricity in hybrid multiferroic calamitic liquid crystal solar cells by incident light illumination makes them potential candidate for various device applications apart from photovoltaic solar cells such as fiber optic systems, optical scanners, wireless LAN, automatic light controls, machine vision systems, electric eyes, optical disk drives, optical memory chips, remote control devices, responsive display devices and light emitting diodes and light shutters.
[0028] Achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate based lyotropic ferroelectric calamitic liquid crystal electrolyte is applied as electrolyte in this invention. The differential scanning calorimetry (DSC) of the applied lyotropic ferroelectric calamitic liquid crystal electrolyte is given in figure 12 an the detailed study will be reported in different work, In hybrid multiferroic calamitic liquid crystal solar cells, lyotropic liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate adsorbed on the surface of n-type semiconducting titania layer and p-type semiconducting light absorbing inorganic sensitizer (N719) through passivation. The nature of the lyotropic ferroelectric calamitic liquid crystal electrolyte applied within the structure of hybrid multiferroic calamitic liquid crystal (HMLC) solar cell along with titania and sensitizer layers is multiferroic. Furthermore, the HMLC solar cells with lyotropic ferroelectric electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate show hysteretic behavior of photovoltaic-current.











AIMS OF THE INVENTION
Some of the aims of the present disclosure are described herein:
[0029] The main aim of the present invention is to overcome SHOCKLEY-QUEISSER PCE limit of p-n junction solar cells through single junction hybrid multiferroic calamitic liquid crystal solar cell.
[0030] Another aim of the present invention is to provide lyotropic ferroelectric calamitic liquid crystal electrolyte to reach PCE value above one hundred (100) % in hybrid multiferroic calamitic liquid crystal solar cells.
[0031] Yet another aim of the present invention is to provide a hybrid multiferroic calamitic liquid crystal solar cell without containing any toxic metal.
[0032] Another aim of the present invention is to provide a low cost and stable hybrid multiferroic calamitic liquid crystal solar cell with high PCE value.
[0033] Another aim of the present invention is to achieve hybrid ferroelectric, ferro elastic, ferromagnetic, piezoelectric, multiferroic and metamaterial solid-liquid crystal composite for light absorption in solar cell and other applications.
[0034] Other aims and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings, which are incorporated for illustration of preferred embodiments of the present invention and are not intended to limit the scope thereof.






SUMMARY OF THE INVENTION
[0035] In view of the foregoing, an embodiment herein provides a stable hybrid multiferroic calamitic liquid crystal (HMLC) solar cell with PCE above SQ limit through incorporating lyotropic ferroelectric electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate. In addition, above 100 % PCE value is achieved in HMLC solar cells.
[0036] According to an embodiment, the hybrid multiferroic calamitic liquid crystal (HMLC) solar cell comprising a first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode; wherein the inorganic n-type semiconductor includes titania with particle size of 20 nm and nano-crystalline TiO2 , Solaronix ®; a second thin layer of light absorbing inorganic sensitizer deposited above the first layer; wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode; a third layer lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate (TCI Chemicals ®) is applied between the light absorbing electrode and light reflecting metal (Pt) electrode which is multiferroic along with titania and inorganic sensitizer; and a fourth layer of reflective platinum (Pt) deposited FTO glass-electrode configured to act as the light reflecting electrode; wherein the general structure of ferroelectric or multiferroic solar cell (metal/ferroelectric (or) multiferroic/metal) is achieved through metal-oxide (FTO) and metal (Pt) electrodes and the multiferroic solid-liquid crystal composite. The polarization direction of multiferroic solid-liquid crystal composite decides the movement of electrons either towards FTO metal oxide electrode or towards Pt metal electrode in HMLC solar cells. The electron injection is ballistic in nature within HMLC solar cell. If the injection of electrons at FTO metal-oxide electrode (light absorbing electrode), it will act as anode and Pt metal electrode (light reflecting electrode) will act as cathode in HMLC solar cell. If the injection of electrons at Pt metal electrode (light reflecting electrode), it will act as anode and FTO metal-oxide electrode will act as cathode in HMLC solar cell. In such a way, switching of photocurrent sign (+, -) occurs in HMLC solar cells through up and down directions of polarization of hybrid multiferroic solid-liquid crystal composite.
[0037] According to an embodiment, the n-type inorganic semiconductor is deposited on conductive fluorine doped tin oxide (FTO) glass-electrode by screen printing method.
[0038] According to an embodiment, the light absorbing inorganic sensitizer (N179) is deposited above the first layer by soaking process.
[0039] According to an embodiment, the inorganic sensitizer is N719 [cis- diisothiocyanato-bis(2,2-bipyridyl-4,4dicarboxylato)ruthenium(II)bis tetra butyl ammonium] sensitizer (acetonitrile and tert-butyl alcohol; 1:1). N719 was purchased from Solaronix ®.
[0040] According to an embodiment, lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate (TCI Chemicals ®) is applied in HMLC solar cell. The lyotropic ferroelectric calamitic liquid crystal electrolyte is toxic metal free. The power conversion efficiency value of hybrid multiferroic calamitic liquid crystal solar cell (light scan 1) is 683.6399 % and its open circuit photo voltage (Voc) value is 9.1256 V and its short-circuit current (Jsc) value is 132.5217 (mA/sq.cm) and its fill factor value (FF) is 56.53 %. The power conversion efficiency of HMLC solar cell (light scan 4) is 97.7431 % and its open-circuit voltage (Voc) value is 5 V and its short-circuit current (Jsc) value is 34.0407 mA/sq.cm and its fill factor (FF) is 41.14 %. The PCE value above SQ limit (30%) as well as PCE value above 100 % are achieved in few light scans of hybrid multiferroic calamitic liquid crystal solar cells (Table 1).
[0041] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.























BRIEF DESCRIPTION OF DRAWINGS
[0042] The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit (s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.
[0043] Fig. 1 illustrates a schematic representation of different layers and components of hybrid multiferroic calamitic liquid crystal solar cell, according to an embodiment of the present invention herein;
[0044] Table 1 illustrates the performances of hybrid multiferroic calamitic liquid crystal (HMLC) solar cells (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate (Voc: Open-circuit voltage, Jsc: Short-circuit current, FF: Fill factor, PCE; Power conversion efficiency) and the photo-active area of HMLC solar cell is 0.2 sq.cm.
[0045] Table 1 illustrates the composition of lyotropic ferroelectric calamitic
liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl
carbonate in tert-butyl pyridine
[0046] Fig. 2 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 1) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0047] Fig. 3 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 2) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0048] Fig. 4 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 3) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0049] Fig. 5 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 4) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0050] Fig. 6 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 5) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0051] Fig. 7 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 7) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0052] Fig. 8 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scan 9) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0053] Fig. 9 illustrates a hysteretic (switching) behavior of the photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under dark condition (dark scans 1 to 3) while applying different sign of bias voltage, according to an embodiment of the present invention herein;
[0054] Fig. 10 illustrates External Quantum Efficiency & Internal Quantum Efficiency vs. wavelength characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate as electrolyte from 300 nm to 1100 nm, according to an embodiment of the present invention herein;
[0055] Fig. 11 illustrates the steady-state photo-current characterization of the hybrid multiferroic calamitic liquid crystal solar cell (I) with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under continuous illumination of sunlight with 0 V bias potential and 5 V bias potential, according to an embodiment of the present invention herein;
[0056] Fig. 12 illustrates differential scanning calorimetry (DSC) characterization of lyotropic ferroelectric calamitic liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate.
[0057] Fig. 13 illustrates the photograph of the measured hybrid multiferroic calamitic liquid crystal solar cell after several light and dark I-V measurements.




















DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0058] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0059] As mentioned above in this context, there is a need to develop a stable hybrid multiferroic liquid crystal solar cell by incorporating lyotropic liquid crystal electrolyte for attaining improved power conversion efficiency (PCE) above SQ limit. The embodiments herein achieve this by providing a stable hybrid multiferroic calamitic liquid crystal solar cell by incorporating lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate.
[0060] Fig. 1 illustrates a schematic representation 100 of different layers and components of hybrid multiferroic calamitic liquid crystal solar cell, according to an embodiment of the present invention. According to an embodiment, the hybrid multiferroic (MF) calamitic liquid crystal solar cell comprising a first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode 101; wherein the inorganic n-type titania semiconductor includes Solaronix ® titania paste with particle size of 20 nm and nano-crystalline TiO2 102; a second thin layer of light absorbing ruthenium based inorganic sensitizer (N719) 103 deposited above the first layer; wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode; a third layer of lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate 104 is applied between the light absorbing and light reflecting electrodes; and a fourth layer of reflective platinum deposited FTO glass-electrode 105 configured to act as the light reflecting electrode. Here the solid-liquid crystal multiferroic composite is in sandwich structure between the metal-oxide (FTO) and metal (Pt) electrodes. The polarization direction of multiferroic solid-liquid crystal composite decides the movement of electron direction towards either metal-oxide (FTO) electrode or metal (Pt) electrode. The movement of electron direction between these two electrodes can be altered and the anode and cathode can be altered within hybrid multiferroic calamitic liquid crystal solar cells through polarization direction. The FTO glass-electrode is purchased from Solaronix ®.
[0061] According to an embodiment, the n-type inorganic semiconductor titania is deposited on conductive fluorine doped tin oxide (FTO) glass-electrode 101 by screen printing method. According to an embodiment, the light absorbing inorganic sensitizer 103 is deposited above the first layer by soaking process. The first layer is baked at 450 °C for 30 minutes and then soaked in 0.0005 M concentration of the light absorbing inorganic sensitizer 103 solution for 18 hours. According to an embodiment, the inorganic sensitizer 103 is N719 [cis- diisothiocyanato-bis (2, 2-bipyridyl-4,4dicarboxylato) ruthenium (II) bis (tetrabutylammonium] sensitizer (acetronitrile and tert-butyl alcohol; 1:1). The N719 [cis- diisothiocyanato-bis (2, 2-bipyridyl-4,4dicarboxylato) ruthenium (II) bis (tetrabutylammonium] sensitizer (acetronitrile and tert-butyl alcohol; 1:1) is purchased from Solaronix ®. Thermo-plastic spacer Solaronix ® with 25 micron thickness is used between the two light absorbing and the light reflecting electrodes.
[0062] According to an embodiment, lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate is component 104. The lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate 104 is iodine free and toxic metal free.
[0063] The lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate consists of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate (TCI chemicals ®), lithium bis(trifluoromethanesulphonyl)imide (Sigma Aldrich ®) and tert-butyl pyridine (TCI chemicals ®) and its chemical composition is given in Table 2. The hysteretic behavior of photo-current vs photo-voltage of hybrid multiferroic calamitic liquid crystal solar cells with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate confirms its role in ferroelectric behavior of HMLC solar cells and it is shown in Fig. 2 to Fig. 8.
[0064] Fig. 2 to Fig. 8 illustrates a hysteretic behavior of photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under illumination of sunlight (light scans 1, 2, 3, 4, 5, 7 and 9) and Fig. 9 illustrates photo-current vs. photo-voltage characterization of the hybrid multiferroic calamitic liquid crystal solar cell with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate under dark condition (dark scans 1, 2 and 3), according to an embodiment of the present invention herein. The photovoltaic performances of the hybrid multiferroic calamitic liquid crystal solar cells (I) are given in Table 1 with voltage pulse values along with their direction. The high power conversion efficiency (PCE) achieved in HMLC solar cell (I) during light scan (1) is 683.6399 % with open-circuit photo-voltage Voc = 9.1256 V, short-circuit current Jsc = 132.5197 mA/sq.cm, fill factor = 56.53 % and the corresponding applied voltage pulse value is in the range from +20 V to -20 V under illumination of air-mass 1.5 solar illumination and the light scan was carried out in cyclic for this measurement. The high power conversion efficiency (PCE) achieved in HMLC solar cell (I) during light scan (4) is 96.7431 % with open-circuit photo-voltage Voc = 5 V, short-circuit current Jsc = 44.2558 mA/sq.cm, fill factor = 43.72 % and the corresponding applied voltage pulse value is in the range from +10 V to -10 V under illumination of air-mass 1.5 solar illumination and the light scan was carried out in cyclic for this measurement. The high power conversion efficiency (PCE) achieved in HMLC solar cell (I) during light scan (5) is 44.8419 % with open-circuit photo-voltage Voc = 3.2020 V, short-circuit current Jsc = 34.0407 mA/sq.cm, fill factor = 41.14 % and the corresponding applied voltage pulse value is in the range from +5 V to -5 V under illumination of air-mass 1.5 solar illumination and the light scan was carried out in cyclic for this measurement. The above 100 % PCE value of HMLC solar cell (I) is the confirmation of exciton fission or multi-exciton generations (MEG) in HMLC solar cell. The above 100 % PCE value achieved in hybrid multiferroic calamitic liquid crystal solar cell with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate with voltage pulse value from +20 V to -20 V. Here the applied external bias voltage is less than the earlier report (60 V). Ananda Rama Krishnan SELVARAJ [IND. Pat. Appl. 202441081731 (2024), UK. Pat. Appl. GB2415881.8 (2024), US. Pat. Appl.18929670 (2024)]. The external bias potential value was reduced here by changing the liquid crystal system without altering the layer thickness of semiconductors in hybrid multiferroic calamitic liquid crystal solar cell. Further the alignment changes in lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate on the surface of N719/TiO2 layers achieved with less bias potential and its impact shown in the short-circuit current (Jsc) values 132.5197 mA/sq.cm (20 V bias scan), 44.2558 mA/sq.cm (10 V bias scan), 34.0407 mA/sq.cm (5 V bias scan) of HMLC solar cell (I). Moreover, the achieved short-circuit current (Jsc) value of HMLC solar cell (I) is the tunneling current and it is directly proportional to applied voltage pulse value. The above SQ limit (30 %) PCE value of HMLC solar cell (I) is reproduced by few light scan (I-V) measurements. The metal-oxide and metal electrodes of HMLC solar cells are light absorbing and light reflecting electrodes, respectively. In typical multiferroic solar cells both electrodes are same kind of metal, and their hysteresis of current-voltage is symmetric. Due to metal-oxide and metal electrodes the asymmetric hysteretic behavior in I-V characteristics of hybrid multiferroic calamitic liquid crystal solar cell is found. In other term, impartial switching of polarization in upward or downward direction can be reason for it. The detailed study is necessary to know more about the asymmetric hysteretic behavior in I-V characteristics.
[0065] The Voc value of hybrid multiferroic calamitic liquid crystal solar cell originates from the ferroelectric polarization value (P) across the hybrid multiferroic solid-liquid crystal composite between the metal and metal oxide electrodes and it is directly proportional to polarization value and photoactive area (A) of hybrid multiferroic liquid crystal solar cell as Voc  P A . Furthermore, the achieved maximum open-circuit voltage (Voc) value of HMLC solar cell (I) is 11.2357 V and the corresponding photoactive area of HMLC solar cell (I) is 0.2 sq.cm only. In addition, a linear correlation was found between the open-circuit voltage (Voc) value and applied bias potential during I-V scan of HMLC solar cells and the achieved Voc values in HMLC solar cells can be termed as the "tunneling photo-voltage" or as "anomalous photo-voltage or bulk photo-voltage" of HMLC solar cell. The achieved Voc value is much higher than the band gap value differences of applied semiconducting materials in HMLC solar cells.
[0066] Fig. 10 illustrates the external quantum efficiency (EQE) and internal quantum efficiency (IQE) vs. wavelength characteristics of hybrid multiferroic calamitic liquid crystal solar cell with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate. The IQE value is above 100 % from 300 nm to 1000 nm and it is the evidence for the multiexciton formation within hybrid multiferroic calamitic liquid crystal solar cell under illumination.
[0067] Fig. 11 illustrates steady-state photo-current vs. time characterization of hybrid multiferroic calamitic liquid crystal solar cell with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate. The measurements were carried out with 0 V bias potential and 5 V bias potential. The obtained photo-current values are supporting the achieved high short-circuit current values during I-V characterization (light scans) of HMLC solar cells.
[0068] Fig. 12 illustrates the differential scanning calorimetry (DSC) of lyotropic ferroelectric calamitic liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate.
[0069] The hysteretic behavior in the photovoltaic current values of hybrid multiferroic calamitic liquid crystal solar cells are found with lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate and reported here.
[0070] The ferroelectric calamitic liquid crystal electrolyte 104 is capable of avoiding the nucleation of crystal growth in multiferroic tunnel junction in hybrid multiferroic calamitic liquid crystal solar cells and therefore there is no trap of electrons and holes, and it is a potential energy barrier free electron tunneling transfer mechanism. The Voc value of hybrid multiferroic liquid crystal solar cells does not depend on the band gap difference of semiconductors and it depends on polarization value of hybrid multiferroic solid-liquid crystal composite within hybrid multiferroic calamitic liquid crystal solar cell.
[0071] The above 100 % IQE value of hybrid multiferroic calamitic liquid crystal solar cell confirms the multiexcitons formation within hybrid multiferroic calamitic liquid crystal solar cell under illumination. The possible ways for multiexciton formation in hybrid multiferroic calamitic liquid crystal solar cell will be the intramolecular or intermolecular singlet exciton fission or impact ionization or it will be a synergic effect. Furthermore, the GOLDSTONE mode of lyotropic ferroelectric calamitic liquid crystal contribution in multiexciton formation might be through formation of new "quasiparticle" namely "electromagson" and the evidence for its formation is not given in this patent application and the high short-circuit current value of hybrid multiferroic calamitic liquid crystal solar cell will be indirect evidence for its formation under solar illumination during I-V measurements. The liquid crystalline phason dynamics (GOLDSTONE mode) induced electron transport and increased conductivity or superconductivity can be understood through high short-circuit current values in light, dark and steady state conditions. The exact mechanism for above 100 % IQE in hybrid multiferroic liquid crystal solar cell is not clear at the moment and further transient absorption investigations are necessary to understand more about these excitons.
[0072] The main advantage of the present invention is that lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate is provided to improve power conversion efficiency of the hybrid multiferroic calamitic liquid crystal solar cell.
[0073] Another advantage of the present invention is that hybrid multiferroic calamitic liquid crystal solar cell is achieved without containing any toxic metal.
[0074] Yet another advantage of the present invention is that a low cost and energy efficient hybrid multiferroic calamitic liquid crystal solar cell is achieved.
[0075] Another advantage of the present invention is that particular composition of the electrolyte has other application that include but they are not limited to nonlinear optics (NLO) applications and optoelectronics applications and piezoelectric applications and magnetoelectronics applications. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
I claim:

1. Hybrid multiferroic calamitic liquid crystal (HMLC) solar cell comprising the metal oxide(FTO)/multiferroic solid-liquid crystal composite/metal (Pt):
the first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode;
wherein the inorganic n-type semiconductor includes Solaronix D(sp) ® paste with particle size of 20 nm and nano-crystalline TiO2;
the second thin layer of light absorbing inorganic sensitizer deposited above first layer;
wherein the inorganic sensitizer includes Solaronix ® ruthenium sensitizer compound N719 [cis-diisothiocyanato-bis(2,2-bipyridyl-4,4dicarboxylato) ruthenium (II) bis (tetrabutylammonium];
wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode;
the third layer of lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate applied between the light absorbing and light reflecting electrodes; and
the fourth layer of platinum deposited FTO glass-electrode configured to act as the light reflecting electrode.

2. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1, wherein power conversion efficiency of the solar cell is 683.6399 % and its open-circuit voltage is 9.1256 V and its short-circuit current is 132.5217 mA/sq.cm, and its internal quantum efficiency value (IQE) is above 100 % and its above 100 % IQE value confirms the multi exciton generation (MEG).

3. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1, wherein power conversion efficiency of the solar cell is 44.8419 % and its open-circuit voltage is 3.2020 V and its short-circuit current value is 34.0407 mA/sq.cm and the applied bias potential for this I-V measurement is 5 V in a cyclic mode.

4. Hybrid multiferroic solid-liquid crystal calamitic liquid crystal composite in
HMLC solar cell as claimed in claim 1, wherein hybrid solid-liquid crystal is ferroelectric, ferromagnetic, ferroelastic, piezoelectric, multiferroic and metamaterial composite.

5. Hybrid multiferroic calamitic liquid crystal solar cell as
claimed in claim 1, wherein it is a hybrid multiferroic solid-liquid crystal tunnel junction diode.

6. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1,
wherein electron-tunneling is demonstrated in multiferroic solid-liquid crystal composite thin-film with few micro-meter level of layer thickness.

7. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1,
wherein the solar cell with power conversion efficiency above p-n junction SHOCKLEY-QUEISSER power conversion efficiency limit (30 %) is achieved and the solar cell with power conversion efficiency above one hundred (100) % is achieved and the hypothetical particle "Electromagson" is found, and it is realized at GOLDSTONE mode of ferroelectric liquid crystals.






Abstract

HYBRID MULTIFERROIC CALAMITIC LIQUID CRYSTAL SOLAR CELL WITH AMYL-4-(4-ETHOXYPHENOXY)PHENYL CARBONATE ELECTROLYTE

The present invention provides hybrid multiferroic calamitic liquid crystal solar cell by incorporating lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate for improving power conversion efficiency of the solar cell. Hybrid multiferroic calamitic liquid crystal (HMLC) solar cell comprises a first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode 101, a second thin layer of light absorbing inorganic sensitizer 103; wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode, a third layer of lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate is as a ferroelectric calamitic liquid crystal electrolyte at room temperature 104 applied between the light absorbing electrode and a light reflecting electrode and a fourth layer of reflective platinum deposited FTO glass-electrode 105 configured to act as the light reflecting electrode. The components between the two electrodes (metal oxide, metal) act as multiferroic solid-liquid crystal composite. The direction of movement of electrons between two electrodes can be altered through the polarization direction of multiferroic solid-liquid crystal composite. It means the anode and the cathode can be altered within hybrid multiferroic calamitic liquid crystal solar cell through the change in the direction of ferroelectric polarization between two electrodes (metal oxide, metal).

ABSTRACT (Fig.)

, Claims:I claim:

1. Hybrid multiferroic calamitic liquid crystal (HMLC) solar cell comprising the metal oxide(FTO)/multiferroic solid-liquid crystal composite/metal (Pt):
the first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass-electrode;
wherein the inorganic n-type semiconductor includes Solaronix D(sp) ® paste with particle size of 20 nm and nano-crystalline TiO2;
the second thin layer of light absorbing inorganic sensitizer deposited above first layer;
wherein the inorganic sensitizer includes Solaronix ® ruthenium sensitizer compound N719 [cis-diisothiocyanato-bis(2,2-bipyridyl-4,4dicarboxylato) ruthenium (II) bis (tetrabutylammonium];
wherein the inorganic sensitizer strained titania FTO glass-electrode acts as a light absorbing electrode;
the third layer of lyotropic ferroelectric liquid crystal electrolyte of achiral amyl-4-(4-ethoxyphenoxycarbonyl)phenyl carbonate applied between the light absorbing and light reflecting electrodes; and
the fourth layer of platinum deposited FTO glass-electrode configured to act as the light reflecting electrode.

2. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1, wherein power conversion efficiency of the solar cell is 683.6399 % and its open-circuit voltage is 9.1256 V and its short-circuit current is 132.5217 mA/sq.cm, and its internal quantum efficiency value (IQE) is above 100 % and its above 100 % IQE value confirms the multi exciton generation (MEG).

3. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1, wherein power conversion efficiency of the solar cell is 44.8419 % and its open-circuit voltage is 3.2020 V and its short-circuit current value is 34.0407 mA/sq.cm and the applied bias potential for this I-V measurement is 5 V in a cyclic mode.

4. Hybrid multiferroic solid-liquid crystal calamitic liquid crystal composite in
HMLC solar cell as claimed in claim 1, wherein hybrid solid-liquid crystal is ferroelectric, ferromagnetic, ferroelastic, piezoelectric, multiferroic and metamaterial composite.

5. Hybrid multiferroic calamitic liquid crystal solar cell as
claimed in claim 1, wherein it is a hybrid multiferroic solid-liquid crystal tunnel junction diode.

6. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1,
wherein electron-tunneling is demonstrated in multiferroic solid-liquid crystal composite thin-film with few micro-meter level of layer thickness.

7. Hybrid multiferroic calamitic liquid crystal solar cell as claimed in claim 1,
wherein the solar cell with power conversion efficiency above p-n junction SHOCKLEY-QUEISSER power conversion efficiency limit (30 %) is achieved and the solar cell with power conversion efficiency above one hundred (100) % is achieved and the hypothetical particle "Electromagson" is found, and it is realized at GOLDSTONE mode of ferroelectric liquid crystals.

Documents