Materials For Photovoltaic Devices Research Articles

Extraction of Silica from Natural Deposits for the Production of Silicon in Photovoltaic Applications

The growing demand for renewable energy sources has driven extensive research and development in photovoltaic technologies. Silicon, in the form of single-crystalline or multi-crystalline wafers, dominates the photovoltaic industry due to its well-established fabrication processes and desirable electrical characteristics Silicon (Si) has long been recognized as the primary material in photovoltaic devices due to its excellent electrical properties and abundance. In this work, we provide a comprehensive review of the elaboration process of silicon for photovoltaic applications. We discuss the various techniques used to produce high-quality silicon, the main steps of the silicon elaboration process can be summarized as: Raw material preparation: Quartz sand, primarily composed of Silicon dioxide (SiO2), undergoes thorough treatment to eliminate undesired impurities. It is subjected to processes such as washing, crushing, and purification to obtain high-quality raw material. Silica reduction: The SiO2 raw material is then subjected to a high-temperature chemical reaction to reduce it into metallurgical silicon (Si). Various methods, including carbothermic reduction, are employed for this process. In carbothermic reduction, carbon, typically in the form of coke, acts as a reducing agent to react with the silica and produce pure silicon. Also the purification methods, and crystal growth techniques. Furthermore, we highlight the importance of silicon's material properties and their impact on photovoltaic device performance. The aim of work is to provide a deeper understanding of the elaboration of silicon we explore our chemical methods used to produce high-quality silicon, including the purification techniques and silicon precursor synthesis and its crucial role in the development of efficient and sustainable photovoltaic technologies.

Variability of temperature on the electrical properties of heterostructured CIS/Cds through SCAPS simulation for photovoltaic applications

Renewable energy research has received tremendous attention in recent years in a quest to circumvent the current global energy crisis. This study carefully selected and simulated the copper indium sulfur ternary compound semiconductor material with cadmium sulfide owing to their advantage in photovoltaic applications. Despite the potential of the materials in photovoltaic devices, the causes of degradation in the photovoltaic efficiency using such compound semiconductor materials have not really been investigated. However, electrical parameters of the materials such as open circuit voltage, short circuit current density, and fill factor have been extensively studied and reported as major causes of degradation in materials’ efficiency. Furthermore, identifying such electrical characteristics as a primary degradation mechanism in solar cells, this study work is an ardent effort that investigates the materials' electrical behavior as a cure to the degradation associated with compound semiconductor-based photovoltaic. In this study, we numerically characterized the electrical properties such as fill factor, open circuit voltage, short circuit current density, power conversion efficiency, net recombination rate, net generation rate, generation current density, recombination current density, hole current density, electrons current density, energy band diagram, capacitance–voltage, electric field strength of the heterostructured CIS/CdS compound semiconductor material using SCAP-1D. We also investigated the effect of temperature on the electrical properties of heterostructured materials. The obtained results reveal the uniformity of the total current density in the material despite the exponential decrease in the electron current density and the exponential increase in hole current density. The extracted solar cell parameters of the heterostructured CIS/CdS at 300 K are 18.6% for PCE, 64.8% for FF, 0.898 V for Voc, and 32 mA cm−2 for Jsc. After the investigation of the effect of temperature on the CIS/CdS compound semiconductor material, it was observed that the solar cell was most efficient at 300 K. The energy band gap of the CIS/CdS compound semiconductor material shrinks with an increase in temperature. The highest net recombination rate and recombination current is at 400 K, while the net generation rate and generation current density are independent of temperature. The study, on the other hand, gave insights into the potential degradation process, and utilizing the study’s findings could provide photovoltaic degradation remediation.

Solvent-free one-pot two component synthesis. Tuning of optoelectronic properties of fluorescent phloroglucinol-aryl Schiff base compounds

A series of new aryl-Schiff base derivatives were synthetized from the one-pot approach: two component condensation reaction in absence of solvent, in quantitative yields with a high atom economy under green conditions. All of the derivatives were fully characterized by NMR, vibrational absorption analysis, UV/vis absorption and fluorescence spectroscopy, and high-resolution mass spectrometry. The aryl-Schiff bases predominantly present the enol-imine tautomer in acetone-d6, while both enol-imine and keto-imine tautomer readily concur in dimethyl sulphoxide-d6. The emission of the series could be tailored by substituting electron donor or electron acceptor groups in the aryl-Schiff bases from fluorescent to not fluorescent molecules, respectively. Fluorescent molecules emit blue, cyan and yellow color with quantum yields in the 2.4–6.2 % range and average lifetime of ∼0.2 ns. The large Stokes’ shift for the molecule bearing a methylalcoxy (3248 cm−1) and diethyl amine (5017 cm−1) suggests a possible intramolecular charge transfer process as also corroborated by cyclic voltammetry, and explaining their low fluorescence quantum yield. The aryl-Schiff base substituted with the methylalcoxy (2b) was used as an electron donor material in photovoltaic devices in configuration: ITO/PEDOT:PSS/2b:PC61BM/Fields metal. The device built under atmospheric conditions displayed an intrinsic power conversion efficiency of PCE ∼0.4 %, with a Voc of 420 mV and Jsc 4.28 mA/cm2.

Theoretical and computational exploration of electronic structure, optical properties, open circuit voltage, and toxicity of perovskites solar Cell:(Cs2SiX6, X = Cl, Br, and I)

Perovskites are presently being considered as a feasible choice for hole-transport materials in photovoltaic devices. One material that stands out among the options is Cs2SiX6, where X indicates Cl, Br, and I. This material is of special interest due to its potential as a lead-free alternative, offering a variety of halide options. Moreover, several experimental inquiries have exhibited favorable outcomes; nevertheless, their theoretical or computational framework is limited and insufficient. As a result, the present investigation has opted for the crystal Cs2SiX6 and synthesized Cs2SiX6, Cs2SiCl6, Cs2SiBr6 and Cs2SiI6 to examine their electronic structures and optical properties using the DFT functional. The electronic structure of Cs2SnBr6, was calculated using GGA with PBE functional, yielding a band gap of 2.434 eV. It should be noted that the experimental value of Cs2SnBr6 was 2.450 eV. Furthermore, the band gaps of Cs2SiCl6, Cs2SiBr6, and Cs2SiI6 were calculated by GGA with PBE to be 1.540 eV, 1.291 eV, and 0.261 eV, respectively. In this study, various pseudopotential techniques are employed to investigate the electrical structures. Five different densities functional theory (DFT) functionals are utilized to determine the most accurate functional. Additionally, the study focuses on the LDA, a unique junction photovoltaic material. In addition, the six optical properties, specifically absorption, reflection, refractive index, conductivity, dielectric function, and loss function, are calculated to provide additional understanding of material qualities in the presence of visual evidence. The utilization of the Density of States (DOS) and the Partial Density of States (PDOS) was employed in order to calculate the electronic structure and bonding properties. For a material to effectively operate as a single-junction photovoltaic, it is imperative that its band gap remains within the specified range of 0.261–1.540 eV. The materials being discussed are conserved within this designated range and employed for their intended purposes. In summary, our research yields strong evidence suggesting that the aforementioned materials lack carcinogenic qualities and demonstrate only moderate degrees of toxicity. In sharp contrast, it has been observed that perovskites containing lead exhibit considerably higher levels of toxicity.

Numerical study of MoSe2-based dual-heterojunction with In2Te3 BSF layer toward high-efficiency photovoltaics

In this study, molybdenum diselenide (MoSe2)-based dual-heterojunction with Indium Telluride (In2Te3) as an absorber and a back surface field (BSF) layers with Al/ITO/CdS/MoSe2/In2Te3/Ni heterostructure has been studied by SCAPS-1D simulator. To explore the potentiality of layered materials in photovoltaic devices, a detailed investigation has been executed on the CdS window, MoSe2 absorber, and In2Te3 BSF layers at varied layer thicknesses, carrier concentrations, interface and defect densities, resistances, and operating temperatures. The photoconversion efficiency (PCE) of 24.78% with short circuit current J sc of 30.55 mA cm−2, open circuit voltage V oc of 0.95 V, and fill factor FF of 85.5% were obtained in the reference cell (without the In2Te3 BSF layer), while a notably improved PCE of 29.94% (5.16% higher) with J sc of 31.06 mA cm−2, V oc of 1.10 V, and FF of 87.28% was achieved by inserting the In2Te3 BSF layer. With a favorable band alignment and almost similar chemical and physical properties as transitional metal dichalcogenides (TMDCs) materials, the proposed dual heterostructure with CdS, MoSe2, and In2Te3 exhibits huge potential as a photoactive material and paves a pathway for the fabrication of uniquely layered material-based thin, flexible high-efficiency solar cells.

Charge transport through molecular ensembles: Triphenylamine-based organic dyes

Based on the recently synthesized triphenylamine-based organic dyes [https://doi.org/10.1021/acsami.1c11547], several small molecules that can be considered as organic semiconducting materials in photovoltaic devices were theoretically modeled. It is found that these designed dyes with the donor-π conjugated bridge-acceptor (D-π-A) framework show high charge transport properties in the dye-synthesized solar cells (DSSCs). Divers types of π-bridges are explored and the structural, electronic, optical, and charge transport characteristics of considered organic small molecules are studied. Our results revealed the effect of π-bridge in tuning the charge transport properties of the studied dyes. Especially, it is found that the thiazole-based moieties as the most favorable candidate for π-bridges, can be used in the D-π-A backbone of the synthesized dye to improve the photovoltaic performance of the organic semiconductors. For designed organic dyes, the low electron reorganization energies and high intra-molecular coupling created by π-stacking give rise to improved electron and hole mobilities. This approach can be used for improving the semiconducting character of organic dyes in photovoltaic devices.

A Novel Ultra-Low Work Function TbFx for High Efficiency Dopant-Free Silicon Solar Cells.

The ability of carrier selective contact is mainly determined by the surface passivation and work function for dopant-free materials applied in crystalline silicon (c-Si) solar cells, which have received considerable attention in recent years. In this contribution, a novel electron-selective material, lanthanide terbium trifluoride (TbFx ), with an ultra-low work function of 2.4eV characteristic, is presented, allowing a low contact resistivity (ρc ) of ≈3mΩcm2 . Additionally, the insertion of ultrathin passivated SiOx layer deposited by PECVD between TbFx and n-Si resulted in ρc only increase slightly. SiOx /TbFx stack eliminated fermi pinning between aluminum and n-type c-Si (n-Si), which further enhanced the electron selectivity of TbFx on full-area contacts to n-Si. Last, SiOx /TbFx /Al electron-selective contacts significantly improves the open circuit voltage (Voc ) for silicon solar cells, but rarely impacts the short circuit current (Jsc ) and fill factor (FF), thus champion efficiency cell achieved approaching 22% power conversion efficiency (PCE). This study indicates a great potential for using lanthanide fluorides as electron-selective material in photovoltaic devices.

Double-perovskite van der Waals heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) as great potential material in photovoltaic devices

With the development of the material performance requirements of solar photovoltaic device design, heterostructure engineering has been widely studied as an effective method to improve the photoelectric properties of semiconductor materials. However, double perovskite-based van der Waals (vdW) heterostructure is still rare. Here, we formed twelve heterostructure constituted by two-dimensional transition metal-sulfur compounds XS2 (X=Cr, Mo, W) and the CsCl, NaInCl, CsNaInCl, Cl interface of inorganic double perovskite Cs2NaInCl6. By calculating the structure optimization and the surface binding energy based on the density functional theory (DFT), we obtained nine stable vdW heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) with the CsCl, NaInCl, CsNaInCl interface. The electronic properties of heterostructure show that six vdW heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo, W) with CsCl, NaInCl interface are semiconductor heterostructure, among which the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with NaInCl interface and Cs2NaInCl6-WS2 with CsCl interface are type I heterostructure, while the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with CsCl interface and Cs2NaInCl6-WS2 with NaInCl interfaceare are type II heterostructure. The projected density of states of Cs2NaInCl6-XS2(X=Cr, Mo, W) heterostructures show that the VBM, CBM of Cs2NaInCl6 in Cs2NaInCl6-XS2 (X=Cr,Mo) with CsCl interface come from Cs, Cl atoms, respectively and the VBM, CBM of Cs2NaInCl6 in Cs2NaInCl6-WS2 with CsCl interface come from Cl, In atoms, respectively which consistent with the distribution pattern of type I, II heterostructure. The results of light absorption indicate that XS2 broadens the absorption spectrum of Cs2NaInCl6-XS2 heterostructures, enhancing their light absorption capacity. Therefore, the heterostructure Cs2NaInCl6-XS2 (X=Cr, Mo) with CsCl interface and Cs2NaInCl6-XS2 (X=W) with NaInCl interfaceare will be a promising material that can be applied in photovoltaic devices.

Growth of GaN Thin Films Using Plasma Enhanced Atomic Layer Deposition: Effect of Ammonia-Containing Plasma Power on Residual Oxygen Capture.

In recent years, the application of (In, Al, Ga)N materials in photovoltaic devices has attracted much attention. Like InGaN, it is a direct band gap material with high absorption at the band edge, suitable for high efficiency photovoltaic devices. Nonetheless, it is important to deposit high-quality GaN material as a foundation. Plasma-enhanced atomic layer deposition (PEALD) combines the advantages of the ALD process with the use of plasma and is often used to deposit thin films with different needs. However, residual oxygen during growth has always been an unavoidable issue affecting the quality of the resulting film, especially in growing gallium nitride (GaN) films. In this study, the NH3-containing plasma was used to capture the oxygen absorbed on the growing surface to improve the quality of GaN films. By diagnosing the plasma, NH2, NH, and H radicals controlled by the plasma power has a strong influence not only on the oxygen content in growing GaN films but also on the growth rate, crystallinity, and surface roughness. The NH and NH2 radicals contribute to the growth of GaN films while the H radicals selectively dissociate Ga-OH bonds on the film surface and etch the grown films. At high plasma power, the GaN film with the lowest Ga-O bond ratio has a saturated growth rate, a better crystallinity, a rougher surface, and a lower bandgap. In addition, the deposition mechanism of GaN thin films prepared with a trimethylgallium metal source and NH3/Ar plasma PEALD involving oxygen participation or not is also discussed in the study.

Synthesis of KBiFe2O5 by electrospinning: Structural, optical, and magnetic properties

Ferroelectric oxides are currently being studied as absorbing materials in photovoltaic devices due to their spontaneous polarization that facilitates charge separation. KBiFe2O5 (KBFO) is a ferroelectric oxide with a perovskite like structure that has a low band gap; however, it has a relatively low electrical conductivity, which makes it difficult to transport and collect carriers. One way of overcoming that deficiency would be by decreasing the dimensions of the active layer. Thus, in this work, for the first time, nanofibers of KBFO were produced by electrospinning. Aqueous solutions of the ceramic precursors in the form of Fe, K and Bi nitrates were electrospun using poly (vinylpyrrolidone) (PVP) as the carrier. The as-spun fibers were calcinated at different temperatures and times. The pure KBFO phase was obtained after calcination at 750 °C, during 1.5 h at 15 °C/min; the nanofibers had diameters between 300 nm and 800 nm as analyzed by scanning electron microscopy (SEM). The interplanar distances of the (100) and (111‾) planes were 0.78 and 0.37 nm, respectively, as calculated by a VESTA software, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Using a Magnetization-Field (MxH) curve, KBFO was found to be highly paramagnetic with low magnetization. The band gap was measured by spectrophotometry via a Tauc plot, resulting in a value of 1.72 eV. Therefore, KBFO in the form of nanofibers seems to have a high potential as an absorbing material in photovoltaic cells.

(Invited) (Photo)Electrochemical Cells for Hydrogen Production and Carbon Dioxide Utilization

Photoelectrochemical (PEC) and electrochemical cells can produce hydrogen from water and/or can produce useful chemicals from carbon dioxide, and, thus, are the key technologies for construction of carbon neutral society.Direct water splitting using photoelectrochemical cell is one of the promising means to produce hydrogen utilizing solar energy. The most important issue for photoelectrode the central of photoelectrochemical cell is narrow bandgap combined with large reaction driving force. Cu(In,Ga)Se2 (CIGS) which is employed as an absorber material in photovoltaic devices is one of the promising photocathode materials because of its long absorption edge of >1000 nm. [1] However, its driving force for water splitting is limited because of relatively shallow valence band maximum (VBM). The solid solution between ZnSe and CIGS (ZnSe-CIGS) is one of the promising candidates of photocathode material for water splitting because of its long absorption edge, ~900 nm, and large driving force, ~1.0 V. [2] In the present study, we investigated introduction of tellurium during ZnSe-CIGS thin films, and found the tellurium introduction increase grain size of ZnSe-CIGS film. The sequential deposition of Ga-rich layer and In-rich layer resulted in formation of composition gradient which facilitate charge separation thorough conduction band minimum (CBM) gradient. The ZnSe-CIGS base photocathode prepared with employing tellurium introduction and composition gradient showed significantly increased incident photon-to-current conversion efficiencies (IPCEs), close to unity. [3]The electrochemical cell with gas diffusion electrode (GDE) for carbon dioxide reduction reaction (CO2RR) can produce useful chemicals efficiently. Copper species are the catalysts with capable of producing C2 products such as C2H5OH and C2H4. In the present study, Cu2O was examined as an electrocatalyst for CO2RR. A GDE composed of carbon paper coated with Cu2O by electroplating method showed C2H4 production with faradaic efficiency (FE) of >50% and C2H5OH production with FE of >20% under the optimized conditions for >10 hours.References H. Kumagai, T. Minegishi, N. Sato, T. Yamada, J. Kubota, K. Domen, J. Mater. Chem. A, 3, 8300 (2015). H. Kaneko, T. Minegishi, M. Nakabayashi, N. Shibata, K. Domen, Angew.Chem. Int. Ed. 55,15329 (2016). T. Minegishi, S. Yamaguchi, M. Sugiyama, Appl. Phys. Lett. 119, 123905 (2021).

Obtaining the solid solution Sb2S3-xSex by selenization of Sb2S3 film and identifying the thermal processing parameters to achieve recrystallization while maintaining phase-purity

In this work, thin films of the ternary material Sb2S3-xSex with promising optical and electrical properties were developed for its application as absorber material in photovoltaic devices. It was found that 400 °C is the lowest recrystallization temperature at which phase-pure polycrystalline films of Sb2S3-xSex can be obtained. Films were recrystallized in a mixture of S/Se vapor by varying the proportion of Se and the film properties were studied as a function of Se content. The conductivity and photosensitivity were increased with the increase in the amount of Se in films. The activation energies associated with the defects or traps in the films decrease with the amount of Se. The morphology of the film changes significantly depending on the annealing pressure. Films recrystallized in an ambient of S/Se vapor generated from 10 mg each of S and Se at 400 °C and 460 Torr pressure are found to have the optimum band gap, highest photosensitivity, and phase-purity. Assuming an appropriate window layer, the modeling result shows that the obtained film Sb2S0.6Se2.4 has the suitable material properties that can result in solar cells with efficiencies in the range of 27%.

Investigation on substrate effect on physical characteristics of CuO- sprayed thin films suitable for photovoltaic application: Ag/ZnO:Sn (n)/CuO (p)/SnO2:F

ABSTRACT In this paper to compare the growth and optoelectronic properties of copper oxide (CuO) materials suitable for advanced application, CuO layers were synthesized on glass and SnO2:F). The X-ray diffraction analysis showed that CuO nanoparticles were formed in pure monoclinic structure where crystallite size decreases from 37.39 to 33.44 nm when the substrate changed, respectively, from glass to SnO2:F/glass. This crystallite size reduction was related to the energy band gap (Eg) enlargement from 1.455 to 1.525 eV due to the quantum confinement effect. Eg values were almost equal to the theoretical one for converting solar energy into electrical energy and CuO may be used as an absorber material in photovoltaic devices. Electrical characteristics were studied using the impedance spectroscopy technique at room temperature and confirmed by the Hall Effect measurements. CuO/SnO2:F/glass thin films have best electrical parameters and consequently the Ag/ZnO:Sn(n)/CuO(p)/SnO2:F photocell was elaborated and its J-V characteristics were analyzed.

Hybrid Materials and Nanoparticles for Hybrid Silicon Solar Cells and Li-Ion Batteries

Hybrid composites based on inorganic nanomaterials embedded into a polymer matrix have were synthesized and characterized. Oxide semiconductor nanoparticles (SnO, SnO2, TiO2, Ga2O3, and NiO) and Si nanoparticles were employed as inorganic counterparts in the hybrid composite, while a conductive polymer (PEDOT:PSS) with diverse additives was used as the organic matrix. The composites were spin-coated on Si or glass substrates. The potential use of these materials in photovoltaic devices to improve Si surface passivation behavior was investigated. Besides, the use of the nanoparticles as active materials for anodes in Li-ion batteries was evaluated. Some other aspects, such as the durability and stability of these materials, were also assessed.

Poly-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin as a material for photovoltaic devices

Superoxide-initiated anion-radical electrodeposition from solutions in DMSO was used to obtain smooth compact films of poly-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin having a photovoltaic response.

Ba-acceptor doping in ZnSnN2 by reactive RF magnetron sputtering: (002) faceted Ba–ZnSnN2 films

Zn-IV-N2 semiconductors display outstanding optoelectronic behavior and hence developed as an effective thin film absorber materials in photovoltaic devices. However, alkaline-earth metallic dopants can improve the performance of Zn-IV-N2 semiconductors. In view of this, Barium (Ba) acceptor was successfully doped into ZnSnN2 crystal lattice with various dopant concentrations (∼0–7%) by reactive RF magnetron co-sputtering at 450 °C. The orthorhombic structured Ba doped ZnSnN2 (Ba:ZTN) films with preferential orientation along (002) plane were obtained. Hall measurement studies revealed that the type of conduction is changed from the conventional n-type to p-type via Ba doping. The deposited Ba:ZTN films exhibited high hole concentration in the range of 1018-1019 cm−3 with low resistivity of ∼10−1 Ω cm and a reasonable mobility of ∼0.5–5 cm2 V−1 s−1. The doping of Ba at either Zn or Sn site would be responsible for the p-type conductivity in Ba:ZTN films. The variations in the surface properties such as morphology and topography of ZnSnN2 on Ba doping were described by FE-SEM and AFM analysis. Further analysis by UV–Vis–NIR and X-ray photoelectron spectroscopies were also performed in order to reveal the optical performance and chemical bonding, composition of Ba:ZTN thin films. The existence of Ba2+ ions in Ba:ZTN was confirmed by the obtained binding energies from XPS analysis. From the collective results, it is suggested that Ba:ZTN could be employed as effective p-type layer in thin film solar cells.

New Thiophene Imines Acting as Hole Transporting Materials in Photovoltaic Devices

Five new unsymmetric thiophene imines end-capped with an electron-donating amine (−NH2) group were obtained using a simple synthetic route, that is, the melt condensation of 2,5-diamino-thiophene-3...

Organic Salts as p-Type Dopants for Efficient LiTFSI-Free Perovskite Solar Cells.

Despite the ubiquity and importance of organic hole-transport materials in photovoltaic devices, their intrinsic low conductivity remains a drawback. Thus, chemical doping is an indispensable solution to this drawback and is essentially always required. The most widely used p-type dopant, FK209, is a cobalt coordination complex. By reducing Co(III) to Co(II), Spiro-OMeTAD becomes partially oxidized, and the film conductivity is initially increased. In order to further increase the conductivity, the hygroscopic co-dopant LiTFSI is typically needed. However, lithium salts are normally quite hygroscopic, and thus, water absorption has been suggested as a significant reason for perovskite degradation and therefore limited device stability. In this work, we report a LiTFSI-free doping process by applying organic salts in relatively high amounts. The film conductivity and morphology have been studied at different doping amounts. The resulting solar cell devices show comparable power conversion efficiencies to those based on conventional LiTFSI-doped Spiro-OMeTAD but show considerably better long-term device stability in an ambient atmosphere.

Domain Wall Conduction in Calcium-Modified Lead Titanate for Polarization Tunable Photovoltaic Devices

Summary Ferroelectric domain wall (DW) conduction, confirmed in recent experiments, has attracted intense attention due to its promising applications in optoelectronic devices. Herein, we provide theoretical evidence of electric conduction in Pb0.8Ca0.2TiO3 (PCT) DWs. The separation of charge accumulation in DWs, corresponding to the electronic conduction-band minimum (CBM) and valence-band maximum (VBM), weakens the tendency for the electron-hole recombination, thereby providing more efficient channels for charge transfer. We fabricate PCT-based functional photovoltaic devices with polarization tunable charge transfer to exploit the combined conduction and ferroelectric properties of the DW. The photovoltaic performance of the devices can be regulated by the alternation of ferroelectric domains in PCT, caused by variation of the external poling. Our work broadens the applicability of DW conduction and may inspire the future design of high-performance materials in photovoltaic devices.

Development of PBS/CDS Core-Shell Nanocomposites Through Ligand Etching for Optoelectronic Application

Core-shell nanocomposites are of immense interest among the research community for its potential applicabilities in various optoelectronic devices. In this work cadmium sulphide (CdS), lead sulphide (PbS) and their core shell PbS/CdS nanostructures have been synthesized through chemical bath deposition method. Their structural and optical properties are studied accordingly through diffractometric and spectrometric techniques. The phase of the core PbS is cubic zinc blende and of the shell CdS is hexagonal wurtzite confirmed from the XRD data. The optical bandgaps are calculated from the absorption spectra and are found to be 2.2eV for PbS and 2.7eV for CdS whereas for core shell PbS/CdS it reduces to 2.1 eV. The photoluminescence spectroscopy has been done on the samples and the spectra shows a blue shift of its near band gap emission for core PbS when it is coated with shell CdS which is not according to the usual behavior of core shell nanostructures. These optical properties are clearly carrying evidences of cationic ligand exchange between the cadmium and lead ion complexes. The conductivity of the prepared samples are measured at room temperature and it is found to be higher in case of PbS/CdS than the core PbS and shell CdS. The increase of bandgap and conductivity of PbS/CdS is a suitable nature for the application of this material in photovoltaic devices. The quantum yield of the core shell nanocomposites is also greatly enhanced that makes the synthesized nanostructures one of the potential candidates for the application in various optoelectronic devices.