Performance Of Thin-film Solar Cells Research Articles

Simulation study on the performance of Cu2ZnSnS4 thin-film solar cells by CdS-free buffer layer Zn1−xMgxO

Simulation study on the performance of Cu2ZnSnS4 thin-film solar cells by CdS-free buffer layer Zn1−xMgxO

Exploration HTL-Free all inorganic mixed halide perovskite solar cells: effects of 4-ADPA passivation

Abstract The incredible PV performance of thin-film perovskite solar cells has garnered the attention of researchers. Mixed halide perovskite outweighs pure halide perovskite in its ability to optimize PV performance while performing material composition engineering. All inorganic mixed halide (AIMH) perovskite CsPbI2Br has shown stable performance against thermal variations. This study mainly highlights the performance of HTL (Hole transport layer) free, passivated solar cell structure with utilization of the SCAPS-1D simulator. The inclusion of passivation layer 4-ADPA(4-aminodiphenylamine) between active layer CsPbI2Br and the end electrode mitigates the occurrence of charge carrier recombination. The thickness of passivation layer 4-ADPA is optimized for the range 100 nm – 1000 nm, and 100 nm is decided as the optimum width based on the evaluated PV performance of SnO2/CsPbI2Br/4-ADPA/anode. 4-ADPA layer with an optimum thickness of 100 nm, is embedded with a CsPbI2Br layer, and the performance of solar cell has been investigated under the collective impact of BDD (bulk defect density)/thickness of CsPbI2Br for the range (1012 cm-3 to 1018 cm-3)/(50 nm to 500 nm) respectively. Further, this study investigated the capacitance-voltage (C-V), Mott – Schottky (1/C2), and Nyquist plot (C-F) performance of solar cells under the influence of only BDD for two cell configurations (corresponding to maximum and minimum delivered PCE i.e., thickness/BDD is 200nm/1012 cm-3 and 500 nm/1018 cm-3 respectively). The highest 13.27% of PCE is extracted from HTL-free, 4-ADPA passivated all inorganic PSC, at 200nm/1012 cm-3 of thickness/BDD respectively. This technique encourages researchers to explore more cost-effective, HTL-free passivated solar cell structures.

Investigating the potential of WO3 and WS2 as Cd-free buffer layers in Sb2Se3-Based thin-film solar cells: A numerical study with SCAPS-1D software

In this numerical study, the performance of thin-film solar cells (TFSCs) based on Sb2Se3 with WO3 and WS2 materials as Cd-free buffer layers was investigated using SCAPS-1D software. WO3 and WS2 were chosen for their suitable band gaps, good electrical conductivity, and optical transparency. The proposed solar cell structures, Au/Sb2Se3/WO3/ITO and Au/Sb2Se3/WS2/ITO were theoretically examined, considering various factors such as conduction band offset, absorber and buffer layer thickness, doping concentrations, series and shunt resistances, temperature, activation energy, and C–V characteristic. The conduction band offset at the absorber/buffer interface showed spike-like configurations, with values of 0.38 eV and 0.23 eV for the WO3 and WS2 buffer layers, respectively. The optimized thickness for the absorber layer in both structures was 1 μm, while for WO3 and WS2 buffer layers, it was 0.1 μm and 0.05 μm, respectively. The optimized acceptor and donor doping concentrations were 1 × 1016 cm−3 and 1 × 1018 cm−3, respectively. The efficiency of the proposed photovoltaic devices was found to be 9.538 % (with Voc = 0.561 V, Jsc = 30.856 mA/cm2, FF = 55.84 %) and 10.151 % (with Voc = 0.558 V, Jsc = 29.189 mA/cm2, FF = 62.34 %) for structures with WO3 and WS2 buffer layers, respectively. These results suggest that using non-toxic materials like WO3 and WS2 as buffer layers can be an efficient and environmentally friendly alternative to toxic CdS for fabricating cost-effective and highly efficient Sb2Se3-based TFSCs.

Performance of nanoparticle-enhanced thin-film solar cell with near-perfect absorption

This study proposes a thin-film solar cell composed of periodic plasmonic titanium nanoparticles (Ti NPs) and indium phosphide (InP) thin films. By adjusting the size and position of plasma Ti NPs and combining with the transparent conductive layer ITO and anti-reflection layer SiO2, the parameters of InP thin film solar cells can be improved. The experimental results show that the average absorption rate reaches 96 % in the wavelength range of 350–850 nm. The absorption rate reached 99.9 % in multiple wavelength ranges. This study has successfully increased the short circuit current to 31.996mA/cm2, power conversion efficiency (PCE) to 29.634 % and open circuit voltage to 1.053 V of InP thin film solar cells.

Multilayers strategy with a mixed CdTe/ZnTe absorber layer for optical trapping and efficiency improvement in CdTe-based solar – SCAPS modelling

This work is a theoretical contribution to improving the performance of CdTe-based thin-film solar cells (TFSC) by optimising the collection of photons in the absorber structure. The basic data are retrieved from experimental reference work and the reference structure is as follows: CdS/CdTe/ZnTe with an efficiency of 20.16%, where ZnTe is used as a BSF to limit backward recombination. The first approach is to incorporate a ZnTe thin layer at the CdS/CdTe heterojunction, to subdivide the CdTe active layer into two (02) sub-layers and to identify the optimum structure as a function of their position in the stack. Investigating the work function of back contact materials enables to better enhance the device′s performance and stability. To take into consideration the discontinuities in the material properties, grain boundaries and performance loss factors, the impacts of charge carrier capture cross sections, bulk and interfacial defects are investigated. SCAPS software is employed for all the numerical modelling, which enables to calculate the current-voltage (J-V), power-voltage (P-V), external quantum efficiency (EQE) and other PV parameters and to draw energy band diagram to better appraise charge carrier transportation. The doping level in the CdTe active layer, the thicknesses and external temperature are also investigated to optimize our device properties. In terms of the obtained fill factor (FF) and efficiency (PCE), the performances were improved with the following structure CdS/CdTe/ZnTe/CdTe/ZnTe, FF = 81.6% and PCE = 23.45%, with 500 nm thickness of CdTe. These results are opening a promising new perspective in high efficiency CdTe TFSC.

Recent Progress and Challenges in Controlling Secondary Phases in Kesterite CZT(S/Se) Thin Films: A Critical Review

Kesterite-based copper zinc tin sulfide (CZTS) and copper zinc tin selenide (CZTSe) thin films have attracted considerable attention as promising materials for sustainable and cost-effective thin-film solar cells. However, the successful integration of these materials into photovoltaic devices is hindered by the coexistence of secondary phases, which can significantly affect device performance and stability. This review article provides a comprehensive overview of recent progress and challenges in controlling secondary phases in kesterite CZTS and CZTSe thin films. Drawing from relevant studies, we discuss state-of-the-art strategies and techniques employed to mitigate the formation of secondary phases. These include a range of deposition methods, such as electrodeposition, sol-gel, spray pyrolysis, evaporation, pulsed laser deposition, and sputtering, each presenting distinct benefits in enhancing phase purity. This study highlights the importance of employing various characterization techniques, such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, for the precise identification of secondary phases in CZTS and CZTSe thin films. Furthermore, the review discusses innovative strategies and techniques aimed at mitigating the occurrence of secondary phases, including process optimization, compositional tuning, and post-deposition treatments. These approaches offer promising avenues for enhancing the purity and performance of kesterite-based thin-film solar cells. Challenges and open questions in this field are addressed, and potential future research directions are proposed. By comprehensively analyzing recent advancements, this review contributes to a deeper understanding of secondary phase-related issues in kesterite CZT(S/Se) thin films, paving the way for enhanced performance and commercial viability of thin-film solar cell technologies.

Effect of annealing temperature on bismuth vanadate nano thin films for solar cell applications

Bismuth vanadate (BiVO4) has been used as the photoanode electrodes in ferroelectric solar cells owing to its unique combination of properties: a narrow bandgap among ferroelectrics, economic viability, negative conduction band edge, and remarkable stability. The present work explores the fabrication and characterization of BiVO4 thin films prepared via spin coating, with a specific focus on elucidating the influence of the annealing temperature (400–550 °C) on their structural, optical, and photovoltaic properties. From X-ray diffraction (XRD) analysis, it is observed that higher annealing temperatures have promoted the formation of larger grains, enhanced crystallinity, and induced a preferred crystal orientation characteristic of the monoclinic scheelite structure. Tauc plot analysis shows the dependence of the optical band gap on the annealing temperature for BiVO4 thin films. The band gap values have decreased slightly from 2.50 eV at 400 °C to 2.44 eV at 550 °C. This is indicated by the slightly narrowed bandgap, which influences the structure of the material or defect states at higher annealing temperatures. A narrower bandgap allows for the absorption of lower-energy light, potentially improving the light absorption efficiency of BiVO4 thin films in photoanode applications. The influence of annealing temperature on BiVO₄ thin film solar cell performance was investigated further through the analysis of open-circuit voltage (Voc), short-circuit current (Isc) and power conversion efficiency.

Application of UV/O3 treatment enhancing the performance of Sb2Se3 thin-film solar cells

Because of its exceptional photoelectric qualities, exceptional stability, and plentiful element resources, the antimony selenide (Sb2Se3) can be used as an absorber layer. The performance of solar cells needs to be further improved. Comprehending the various surface treatment conditions is instrumental in optimizing device performance. In this research, we pre-treated the fluorine-doped tin oxide (FTO) surface with ultraviolet ozone (UV/O3) and investigated how the device (FTO/CdS (53 nm)/Sb2Se3(203 nm)/Spiro(120 nm)/Au(80 nm)) performance was affected by temperature of the substrate during the UV/O3 treatment. It's interesting to note that the solar cells made with FTO after exposure to UV/O3 have better interface quality and lower recombination losses, which significantly improves the Open circuit voltage (VOC) and Fill factor (FF). The result is an improvement in the device's Power Conversion Efficiency (PCE) from 7.13% to 8.14%. The work is aimed at developing an efficient strategy to improve the performance of Sb2Se3 solar cells.

Vapor-transport-deposited Sb2S3 thin-film solar cells: Tailoring photovoltaic properties through deposition temperature

Crystal orientation plays a crucial role in the performance of Sb2S3 thin-film solar cells (TFSCs). Among various deposition techniques, vapor transport deposition (VTD) stands out as a viable technique for producing scalable and uniformly deposited thin films, particularly in the solar industry. This study explores temperature-modulated VTD-Sb2S3 deposition to enable efficient carrier transport in photovoltaic cells. In the VTD process, the deposition temperature is altered between 480 °C and 540 °C. XRD, SEM, EDS, and AFM techniques are employed to obtain the characteristics of the Sb2S3 thin films at varying temperatures and evaluate critical features like crystal structure and orientation, surface morphology, composition, and roughness. The prominent crystal orientation changes from the (hk0) to the (hk1) plane after increasing the deposition temperature from 500 to 520 °C. The (211)- and (221)-planes become more prominent when the deposition temperature exceeds 520 °C. The device with the architecture SLG/Mo/Sb2S3/CdS/i-ZnO/AZO/Al, a substrate-configured TFSC, yields a maximum power conversion efficiency of 0.22% when the VTD-Sb2S3 absorber film is deposited at 520 °C. This study presents a promising approach to producing thin films with a preference for specific crystal orientations. The primary aim is to enhance the efficiency of solar cells that utilize VTD-Sb2S3 absorbers.

Achieving highly efficient kesterite solar cells using simultaneous surface Ge substitution and rear interface engineering strategies

The progress in the device performance of kesterite-based thin-film solar cells (TFSCs) have been stagnant due to unstable rear contact properties and large open circuit voltage (Voc)-deficit characteristics. Several individual strategies have been developed to solve these issues. In this work, we investigate the simultaneous impact of Ge substitution and rear interface engineering with a MoOx intermediate layer on Mo back contact. The simultaneous application of both strategies delivers a synergetic effect, improving microstructure, Voc-deficit, band-tailing states, and device parameters and reducing Sn-related deep-level defects, resulting in enhanced power conversion efficiency (from 8.1 to 11.55%). This effective strategy offers new insight and a way to solve unstable rear contact properties and large Voc-deficit, further improving the device performances of kesterite-based TFSCs.

Photovoltaic performance of magnetron sputtered antimony selenide thin film solar cells buffered by cadmium sulfide and cadmium sulfide /zinc sulfide

Antimony selenide (Sb2Se3)-based thin-film solar cells have recently attracted worldwide attention as an abundant, low-cost, and efficient photovoltaic technology. The highest efficiencies recorded for Sb2Se3 solar cells have been obtained using cadmium sulfide (CdS) as a buffer layer. The Cd-included hybrid buffer layers could be one option to increase device efficiency through more effective usage of light. Therefore, in this work, the effect of single CdS and hybrid CdS/zinc sulfide (ZnS) buffer layers on the photovoltaic performance of Sb2Se3 thin-film solar cells has been investigated in detail. Sb2Se3 thin films have been deposited on molybdenum (Mo)-coated soda-lime glass (SLG) substrates by radio frequency magnetron sputtering technique followed by a post-heat treatment process. The morphological, and structural properties of Sb2Se3 thin films have been investigated by X-Ray Diffraction and Scanning Electron Microscopy. To compare the device performances of single CdS and hybrid CdS/ZnS buffered Sb2Se3 thin-film solar cells, SLG/Mo/Sb2Se3/CdS/ZnS/indium tin oxide (ITO) and SLG/Mo/Sb2Se3/CdS/ITO structures have been fabricated. The findings of this study have revealed a reduction in solar cells’ performance from η=3.93% for CdS buffer to η=0.13% for CdS/ZnS hybrid buffer. The change in the solar cell performance using the CdS/ZnS hybrid buffer has been discussed in detail.

KCl Treatment of CdS Electron-Transporting Layer for Improved Performance of Sb2(S,Se)3 Solar Cells.

Antimony sulfoselenide (Sb2(S,Se)3) is a promising light absorption material because of its high photoabsorption coefficient, appropriate band gap, superior stability, and abundant elemental storage. As an emerging solar material, hydrothermal deposition of Sb2(S,Se)3 solar cells has enabled a 10% efficiency threshold, where cadmium sulfide (CdS) is applied as an electron transport layer (ETL). The high-efficiency Sb2(S,Se)3 solar cells largely employ CdS as the ETL. In terms of efficiency improvement, there are two questions regarding the CdS substrate: (1) the high roughness of CdS grown on F-doped tin oxide glass which increases the roughness of the absorber layer and (2) the low conductivity of CdS films because of low purity of CdS film grown by chemical bath deposition. In this study, we demonstrate an effective potassium chloride (KCl) post-treatment to modify the CdS ETL for improving the Sb2(S,Se)3 solar cell efficiency. We found that KCl plays dual roles that reduce roughness and enhance conductivity of the CdS films, thus acquiring a maximum efficiency of 9.98%, which is 9.2% higher than the control device. This study provides a new method for the surface engineering of CdS layer to improve the morphological and electrical properties, which is significant for improving the performance of CdS-based thin-film solar cells.

On performance of thin-film meso-structured perovskite solar cell through experimental analysis and device simulation

In the last few years, there has been an unprecedented progress in the increase of the power conversion efficiency of perovskite solar cells. Evidently, further advances in the efficiency of these devices will depend on the constraints imposed by the optical and electronic properties of their constituents. Quite apparently during the manufacturing process of a solar cell, there is an inevitable variation in the thicknesses of various functional layers, which affects the optoelectronic characteristics of the final sample. In this work, a possible strategy of the analysis of the solar cell performance is suggested, based on statistically averaging procedure of experimental data. We present a case study, in which the optoelectronic properties of the meso-structured perovskite solar cell (with a mesoporous TiO2 layer) are analyzed within the method providing a deeper understanding of the device operation. This method enables an assessment of the overall quality of the device, pointing pathways towards the maximum efficiency design of a perovskite solar cell by material properties tuning.

Impact of tellurium as an anion dopant on the photovoltaic performance of wide-bandgap Cu(In,Ga)Se2 thin-film solar cells with rubidium fluoride post-deposition treatment

The development of wide-bandgap Cu(In,Ga)Se2 thin films is crucial in order to reach the theoretical Shockley–Queisser limit values in single-crystal solar cells. However, the performance of solar cells based on wide-bandgap thin film absorbers has lagged significantly compared to that of their narrow-bandgap counterparts. Herein, we develop a feasible strategy to improve the photovoltaic performance of wide-bandgap Cu(In,Ga)Se2 chalcopyrite thin-film solar cells by simultaneously doping with both RbF PDT and Te2− anions as dopants in the absorber layer during the three-stage co-evaporation process. Besides inducing significant change in the GGI gradient, the synergistic effect of the Te2− anion dopant is rather beneficial in terms of controlling grain size, defects in grain boundaries, and charge carrier lifetime for encouraging charge separation and extraction, which contributes to simultaneously boosting short-circuit current density and fill factor. Te-poor devices afford an impressive efficiency of 9.58%, compared to 6.43% for control devices. More importantly, the efficiency and Voc values obtained for wide-bandgap-based thin-film solar cells containing Te anions were the highest compared to their counterparts as reported in the literature. These results demonstrate the role of Te2− anions in wide-bandgap absorber thin films on the photovoltaic performance of thin-film solar cells and the potential of this approach for use in reasonable and effective design of highly efficient wide-bandgap thin-film solar cells.

Isomer-dependent performance of thin-film solar cells based on petroporphyrins

Complexes of etioporphyrin with transition metal ions are abundant in fossil fuels (hence the term petroporphyrins); their isolation from crude material or by laboratory synthesis are well-known procedures. Nonetheless, there are few examples of practical applications of these available and stable materials. We report an attempt to systematically introduce five synthetic etioporhyrin (EtioP) complexes with copper and nickel into archetypal thin-film photovoltaic cells fabricated entirely by vacuum thermal evaporation. It is shown that EtioPs act as effective donors in a planar heterojunction, where another porphyrinoid molecule, hexachloro-subphthalocyanine boron chloride Cl6SubPc, is used as an acceptor. The efficiency of the devices is limited due to the narrow-band absorption by the D/A pair and, hence, insufficient photon capturing from the sunlight spectrum. No clear correlation of the device parameters with the position isomerism or frontier molecular orbital energies of EtioPs is found. Best photovoltaic performance is shown by the Cu-EtioP-II based devices.

Simulation of new thin film Zn(O,S)/CIGS solar cell with bandgap grading

Copper-Indium-Gallium-diSelenide (CIGS) thin film solar cell is a promising candidate for energy harvesting because of its high absorption coefficient and low cost compared to silicon-based solar cells. Absorber layer bandgap grading is a suitable method to improve CIGS thin film solar cell performance. Bandgap grading leads to a decrease in the recombination rate at the rear surface, which increases the open circuit voltage. Furthermore, bandgap grading improves the short circuit current due to the enhancement of collection probability. This paper introduces various routes for improving the performance of thin film CIGS solar cells by using bandgap grading. As a first step, both the bandgap energy and the thickness of the CIGS absorber layer of a uniform bandgap profile are optimized to get the best performance. Simulation is performed using SCAPS software and optimization results show that CIGS absorber layer with a bandgap of 1.2 eV and a thickness of 0.7 μm achieves a 22.48% efficiency. Then, bandgap grading with a parabolic distribution of various profiles is investigated and compared. It is found that with a parabolic double bandgap grading profile, which is a combination of front and back grading, an efficiency of up to 24.16% is achieved. This improvement is obtained using a gallium composition ratio of 0.1 for the minimal bandgap at 0.1 μm and 0.13 μm from the back contact and front contact, respectively. This result represents a 7.47% improvement compared to the baseline structure of a CIGS solar cell.

Effects of "defective" plasmonic metal nanoparticle arrays on the opto-electronic performance of thin-film solar cells: computational study.

This computational study investigates the effects of common defects that occur while fabricating arrays of plasmonic metal nanoparticles (NPs) on the absorbing layer of the solar cells for enhancing their opto-electronic performance. Several "defects" in an array of plasmonic NP arrays on solar cells were studied. The results demonstrated no major changes in the performance of solar cells in the presence of "defective" arrays when compared to a "perfect" array with defect-free NPs. The results indicate that relatively inexpensive techniques may be used to fabricate "defective" plasmonic NP arrays on solar cells and still obtain a significant enhancement in opto-electronic performance.

Improved performance of Cd-free CZTS thin-film solar cells by using CZTS0.4Se0.6 BSF layer

Cu2ZnSnS4 (CZTS) thin film solar cells (TFSCs) have received great attention from the solar cell industry for their environment, price, high absorption coefficient and great electronic properties. This work provides a strategy to prompt the photoelectric conversion efficiency (η) of CdS/CZTS-based TFSCs via introducing the back surface field (BSF) layer and wxAMPS to simulate the results. Meanwhile, the optimum ratio of sulfur to selenium in the BSF layer material CZTSSe has been also studied, and a new device structure has been constructed. Beneficial from the introduction of CZTSSe as a BSF layer, the interface recombination is suppressed and leads to an enhanced Voc. Subsequently, MoO3, ZnS, WO3, TiO2 and In2S3 as candidates to substitute for the toxic Cd buffer layer are investigated. The results demonstrate that In2S3/CZTSSe exhibits the best performance with 28.59 % and 0.99 V, ascribed to a superior spike-like value. It was found that the presence of a spike-like conduction band (CB) at the In2S3/CZTSSe interface and a more suitable conduction band offset (CBO) value could suppress the interfacial complexation. Therefore, In2S3 performs best as a buffer layer material. However, due to the cost of indium, this paper recommends the utilization of wide bandgap semiconductor materials MoO3 and ZnS, which also have good stability and conversion efficiencies that can reach 28.38% and 28.41%, respectively. The work of this paper provides important guidance for researchers to manufacture CZTS TFSCs.

Sputtering Al2O3 as an effective interface layer to improve open-circuit voltage and device performance of Sb2Se3 thin-film solar cells

Sb2Se3 as a promising photovoltaic absorber material is attracting increasing attention. However, high open-circuit voltage (VOC) loss, especially for superstrate structured Sb2Se3 solar cells, is one of the main bottlenecks for improving device efficiency. Here, sputtering aluminum oxide (Al2O3) as an interface layer between CdS and Sb2Se3 was applied in superstrate structured Sb2Se3 solar cells. We proved that the sputtered Al2O3 layer is not fully continuous on the rough CdS film even its thickness has reached 8.8 nm. Then we systematically investigated the influence of the Al2O3 layer on Sb2Se3 material properties and device performances. It is found that the Al2O3 layer can not only effectively inhibit [hk0]-oriented crystal growth and promote [hk1] growth orientation of Sb2Se3 films but also obviously weaken the disordered growth of prominent petal-like shape Sb2Se3 grains and reduce the surface roughness. Further, the Al2O3 layer can also availably passivate interfacial defects at the CdS/Sb2Se3 interface. Consequently, the average power conversion efficiency (PCE) of Sb2Se3 solar cells with an optimal Al2O3 layer thickness is 17.86% higher than that without the Al2O3 layer. Noteworthily, the VOC of Sb2Se3 solar cells is boosted to 0.462 V, which is the highest value in superstrate structured Sb2Se3 solar cells with absorber prepared by conventional physical methods. Finally, a champion efficiency of 6.25% has been achieved in a low-cost Sb2Se3 thin-film solar cell with FTO/CdS/Al2O3/Sb2Se3/Carbon device configuration.

Which Parameters Determine the Low-Light Behaviour of CIGSSe-Based Thin-Film Solar Cells?

The performance of solar cells in realistic operating conditions usually differs from the specified efficiency at standard test conditions (STC). Among other factors, the illumination intensity (irradiance) is often lower than at STC, which leads to a lower device efficiency. Therefore, it becomes important to optimize the output power at low-light conditions in order to achieve a high energy yield at a specific location. For this purpose, it is essential to have a detailed knowledge of the relevant parameters that govern the low-light behaviour. This study investigates the impact of the diode parameters on the low-light performance of thin-film solar cells based on chalcopyrite Cu(In,Ga)(S,Se)2 absorbers. Experimental irradiance-dependent current-voltage results are analysed with the help of an analytical model. For each parameter the contributions of its absolute value and its irradiance dependence are assessed. Additionally, relations between the diode parameters and material parameters are examined by analysing different cell variations. The results show that cell performance at low-light conditions is primarily governed by the irradiance dependence of the fill factor, which in turn is mainly determined by the parallel resistance of the device. Moreover, a reduction of the dark saturation current and the ideality factor towards lower irradiances is observed which indicates an irradiance-dependent change of recombination dynamics. The consequence is an increase of the open-circuit voltage at low-light conditions which indirectly also boosts the fill factor. The results suggest that cell optimization for low-light conditions should focus on improving the parallel resistance and tuning recombination in a way that the dark saturation current decreases with decreasing irradiance.