Efficient Thin Film Solar Cells Research Articles

Point-junction and alkali-assisted surface selenium diffusion: Unveiling a two-step method for enhancing the efficiency of VTD-SnS thin-film solar cells

Surface and interface engineering in thin-film solar cells (TFSCs) is vital for optimizing charge carrier dynamics, reducing recombination, enhancing material properties, and ultimately improving efficiency and overall performance. In this study, e-beam evaporation was used to deposit selenium (Se) onto tin sulfide (SnS) absorber layers with a thickness of 10 nm to 50 nm. The Se layer optimization was validated using various characterization techniques, which confirmed the formation of micro-sized openings via Se droplet deposition. This Se passivation-plus-local opening geometry plays a crucial role in forming point-junctions with the n-type CdS during cell fabrication, presenting a novel approach in state-of-the-art technology. The results revealed a significant enhancement in the conversion efficiency of the SLG/Mo/SnS/Se/CdS/i-ZnO/AZO/Al device to 3.01 % (VOC = 0.326 V, JSC = 20.21 mA cm−2, and FF = 0.45) with 30 nm Se layer deposition. Furthermore, a 30 nm-thick NaF-assisted Se layer was deposited to improve device performance. The diffusion of both Se and Na into the SnS substrate was validated using XRD, SEM, EDS, AFM, and XPS. The power conversion efficiency (PCE) of the SLG/Mo/SnSSe-NaF/CdS/i-ZnO/AZO/Al device was further enhanced to 3.70 % (VOC = 0.340 V, JSC = 22.56 mA cm−2, and FF = 0.48). This enhancement is attributed to the creation of localized junctions via Se surface passivation, and the concurrent SnSSe formation induces band gap tuning and increases the grain size, contributing to additional PCE improvement during Na-assisted Se diffusion.

Optimizing thin-film silicon solar cells with nanostructured TiO2 and a silver back reflector for enhanced energy conversion efficiency

This paper investigates the improvement of energy conversion efficiency in thin-film silicon solar cells by employing periodic nanostructures of TiO2 on the silicon active layer and a back reflector featuring periodic nanostructures of silver. The objective is to increase the optical path length, enhance absorption probability for longer wavelengths, and subsequently improve solar cell performance. Three silicon-based solar cell configurations are proposed and simulated using the finite difference time domain (FDTD) method to assess their performance. Electrical characteristics are obtained through the drift-diffusion method. The resulting short-circuit current density increased from 40.93 to 65.28 to 95.373mA/cm2 for the three cells, leading to significant improvements in conversion efficiency with observed values of 20.39%, 33.26%, and 47.28%, respectively, in the optimized structures. Furthermore, we compare the simulation results of the three structures with those of a reference structure and several structures previously proposed in the literature.

Designing novel plasmonic architectures for highly efficient CIGS solar cells

CIGS solar cells is one of the best thin film solar cells which have efficiency up to 22.6 %. In the recent decades, a lot of attention has been drawn to the methods of increasing solar cells efficiencies. One of the emerging technology for enhancing thin film solar cell efficiencies are using plasmonic effects in the visible or infrared part of the electromagnetic spectrum. Therefore, the primary goal of this study is to use plasmonic nanostructures in the active layer to enhance the absorption and consequently the efficiency of a thin film CIGS solar cell with a 1000 nm thickness. Different factors such as type of material, size and surface occupied with nanostructure can be effect on CIGS solar cell performance. In this research, the solar cell has been optically and electrically characterized in the presence of plasmonic nanostructure by simulations. The efficiency was determined by characteristics parameters such as absorption, quantum efficiency, electron-hole generation rate, current–voltage curve and power-voltage curve. Based on our simulations, the maximum efficiency of 25.61 % was achieved using gold nanocubic structures with dimensions of 100 nm, Occupied Factor of 0.16, positioned at the top of the active layer. This increase is due to increase in optical path of length of scattered light and consequently its absorption in the active layer. Moreover, enhancing carrier generation, decreasing recombination and improving carrier separation can be occurred due to localized surface plasmon resonance and the near-field distribution effect, which effectively scatter light into the active layer.

Nickel-doped silver nanoclusters as a mechanism to capture photons

Narrow width of optical absorption of conducting polymers and photons energy losses have been the challenges for fabricating highly efficient thin-film organic solar cell. Nickel-doped silver nanoclusters (Ni/Ag NCs) are employed here to capture more photons using polymers blend solar absorber medium to improve solar cell performances. The poly-3-hexylthiophene and (6-6)phenyl-C61-butyric acid methyl ester molecules blend were used a solar absorber layer in this investigation. The solar cells fabricated with NCs exhibited enhanced opt-electronic properties compared to the reference solar cell. Consequently, the experimental results suggest that the power conversion efficiency (PCE) has substantially increased with the incorporations of NCs in absorber layer, which is dependent on the concentrations of NCs in the medium. The maximum PCE achieved, in this work, is η\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\eta $$\\end{document} = 6.2% at 2% of NCs by weight, which has exhibited to the lowest energy losses compared to other doping levels. This improvement in PCE is attributed to the occurrence of local surface plasmon resonance effect due to the inclusion of Ni/Ag NCs in polymer matrix. The results provide valuable insights on the use of Ni/Ag NCs for efficient photons capture in thin-film polymers blend medium.

Hierarchical pore structure with a confined resonant mode for improving the solar energy utilizing efficiency of ultra-thin perovskite solar cells

The perovskite solar cell (PSC) has the benefits of flexibility, inexpensiveness, and high efficiency, and has important prospective applications. However, serious optical losing and low solar energy-utilizing efficiency remain a challenge for the ultra-thin PSCs because of the interface reflection of traditional planar structure. In this study, a hierarchical pore structure with a confined resonant mode is introduced and optimized by electromagnetic theory to improve the solar energy absorbing and utilizing efficiency of ultra-thin PSCs. The large pores in the top layer that support a whispering gallery mode can focus and guide the incident light into the solar cell. The small pores in the bottom layer enable backward scattering of the unabsorbed light and can improve the effective absorption of active layer. The finite-difference time-domain method is employed to optimize the geometric parameters of hierarchical pore structure to improve the light absorption of PSCs. The proposed resonant hierarchical pore structure can greatly improve sunlight absorption of ultra-thin PSCs, and the effective light absorption and photocurrent of PSCs with a hierarchical pore structure is 20.7% higher than that of PSCs with traditional planar structure. This work can offer a beneficial guideline for improving solar energy utilizing efficiency of various thin-film solar cells.

Buried junction and efficient carrier separation in CdSexTe1−x/CdTe solar cells

Alloying CdTe absorbers with Se is a critical advancement for the fabrication of highly efficient CdTe thin-film solar cells. Herein, the role of the Se concentration gradient in CdSexTe1−x/CdTe solar cells is stressed in addition to the decreased bandgap and passivation effect of Se. The buried graded CdSexTe1−x at the front interface of the device was stripped and analyzed by quasi in situ x-ray photoelectron spectroscopy depth profiling. A serial shift of Fermi level toward the valence band was probed as the Se concentration decreased in the graded CdSexTe1−x absorber, revealing the presence of n-type CdSexTe1−x region near the front contact. Kelvin probe force microscopy characterizations and voltage-dependent photocurrent collection analysis further confirmed the existence of a buried junction in the graded CdSexTe1−x absorber. The CdS-free CdTe solar cell with a graded CdSexTe1−x/CdTe absorber fabricated in this study showed an efficiency of 17.6%. These results indicated that the non-uniform distribution of Se introduced a built-in field in the graded CdSexTe1−x absorber and enabled efficient separation of photogenerated carriers, yielding high-performance CdTe solar cells in the absence of a conventional n-type CdS window layer. This study deepened the understanding of the performance enhancement in Se-containing CdTe solar cells and provided new ideas for further performance optimization.

Regulating the crystal orientation of vapor-transport-deposited GeSe thin films by a post-annealing treatment

Recently, GeSe has emerged as a highly promising photovoltaic absorber material due to its excellent optoelectronic properties, nontoxicity, and high stability. Although many advantages make GeSe well suited for thin-film solar cells, the power conversion efficiency of the GeSe thin-film solar cell is still much below the theoretical maximum efficiency. One of the challenges lies in controlling the crystal orientation of GeSe to enhance solar cell performance. The two-step preparation of GeSe thin films has not yet been reported to grow along the [111] orientation. In this work, we study the effect of a post-annealing treatment on the GeSe thin films and the performance of the solar cells. It was found that amorphous GeSe films can be converted into polycrystalline films with different orientations by changing the post-annealing temperature. [111]-oriented and [100]-oriented GeSe thin films were successfully prepared on the same substrate by optimizing the annealing conditions. With the structure of Au/GeSe/CdS/ITO cell devices, PCEs of 0.14% and 0.16% were ultimately achieved.

ZnxCd1–xSySe1–y as an effective electron transport layer for improving the efficiency of Sb2S3 and Sb2Se3 thin-film solar cells

ZnxCd1–xSySe1–y as an effective electron transport layer for improving the efficiency of Sb2S3 and Sb2Se3 thin-film solar cells

Lead-free perovskite solar cell based on methyl ammonium tin iodide: Possible power conversion efficiency enhancement by device simulation

Although solar cells have the potential to create an endless amount of electrical power, their comparatively low power conversion efficiency draws the curiosity of both academics and industry. The primary goal of this research is to examine the performance of lead-free perovskite solar cells that use methyl ammonium tin iodide (CH3NH3SnI3) as the active material. The SCAPS-1D programme is employed for the simulation and analysis of the solar cells. The solar cell structure was analyzed computationally, and the resulting output was examined by comparing the I-V characteristic curves across different combinations of parameters. Various materials and combinations of parameters were explored in an effort to enhance the power conversion efficiency of solar cells based on CH3NH3SnI3. A series of comprehensive evaluations were undertaken to examine the influence of technical factors, including absorber layer thickness, defect density, and acceptor density, on performance. The acceptor density that yielded the best results was selected in order to improve the performance of the solar cell. The simulation results were acquired across a temperature range spanning from 300K to 450K, revealing enhanced stability within the range of typical ambient temperatures. The study produced encouraging findings, which included a short circuit current density of 30.81mA/cm2, an open circuit voltage of 1.25V, a fill factor of 80.35%, and a power conversion efficiency of 31.11%. This study has the potential to facilitate the development of environmentally sustainable, highly efficient, and cost-effective thin film solar cells based on CH3NH3SnI3, which exhibit noteworthy physical characteristics as alternatives to lead-containing perovskite solar cells.

Improving device performance of sputtered CZTSe based solar cells by Manganese doping

Despite many efforts, Cu2ZnSnSe4 (CZTSe) based solar cells have remained relatively low efficiency compared to other thin film-based devices. One of the prevalent strategies used to improve cell performance in CZTSe is cation substitution. In this contribution, the effects of substituting Mn for Zn on CZTSe solar cell performance were systematically examined. Samples with various Mn content were grown by a two-stage method involving high temperature annealing of precursor layers comprising Cu, Zn, Sn, Mn and Se. All of the samples were found to have Cu-poor and (Zn + Mn)-rich or nearly stoichometric compositions. They crystalized in kesterite phase irrespective of the Mn content as confirmed by X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) measurements. The highest efficiency solar cell (5.56%) was obtained employing the 5% Mn doped CZTSe absorber. This film was found to have improved microstructure and reduced defect density. This is the first report on over 5% efficient kesterite thin film solar cell fabricated on a Cu2Mn0.05Zn0.95SnSe4absorber layer.

Numerical simulation of Cu2Te based thin film solar cell with Cu2O HTL for high efficiency

Copper telluride (Cu2Te) is an attractive semiconductor absorber material for thin film solar cells due to its excellent opto-electronic properties. However, the maximum experimental conversion efficiency of the Cu2Te thin film solar cell remains at about 6%. In the present study, the cuprous oxide (Cu2O) material as the hole transport layer (HTL) has been proposed in the Cu2Te based thin film solar cell. The purpose of this work is to enhance the device performance by inserting widely available Cu2O material as HTL into the basic heterojunction structure. The effects of several material parameters such as thickness, carrier concentration, defect density and back contact metal work function on the device performance of the proposed Cu2Te thin film solar cell consisting of FTO/WS2/Cu2Te/Cu2O/metal have been studied and numerical investigated using the wxAMPS program. Optimized conversion efficiency of the proposed Cu2Te thin film solar cell with Au as back contact metal has been obtained to be 30.32%. These results reveal that the Cu2O material as HTL can be employed to fabricate low cost and highly efficient Cu2Te thin film solar cells.

Current Status and Future Prospects of Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) Thin Film Solar Cells Prepared via Electrochemical Deposition

AbstractThe fabrication of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) thin‐film solar cells using the electrochemical deposition (ED), which is valued for its industrial feasibility, offers a cost‐effective and environmentally friendly approach to the carbon‐free and clean energy production. However, the reported power conversion efficiency of approximately 10 % for electrodeposited CZTSSe thin‐film solar cells is lower compared to the alternative methods like sputtering and spin‐coating, which is mainly attributed to the phase inhomogeneity and the rough morphology generated during the ED process. Ensuring the microscopic and macroscopic uniformity of the electrodeposited films is crucial for the improvement of the film quality and the device performances. In this review, strategies to address these challenges including the intrinsic film control such as the deposition mode, pH, concentration of metal ions, and complexing agents, as well as the extrinsic approaches such as doping, substitution of metal elements, and the introduction of interfacial layers. In addition, the prospects for the electrochemically deposited CZTSSe solar cells were presented, focusing on the promising applications in tandem, flexible, and solar water‐splitting devices. Finally, this review will provide technical insights into the ED process for preparing CZTSSe solar cells, outlining a perspective for the future development of highly efficient CZTSSe thin film solar cells.

A A highly efficient InGaP thin film solar cell structure, optimization and characteristics

Inorganic solar cells based on III-V semiconductor materials are widely used owing to their high efficiencies. In this work, we aim to improve the performance of the single heterojunction solar cell InGaP. The InGaP cell is constituted of a back surface field (BSF), a base, an emitter and a window layer with InAlAsP material. The simulation is done after optimization, modeling, and choice of the used materials and the thickness of different layers constituting the solar cell. The choice of materials whose gap energy is decreasing allows the absorption of the solar spectrum in its almost totality. Then, we varied the temperature to know its effects on the gap energy and the efficiency of the InGaP cell. The InGaP and solar cell with optimal parameters are illuminated by an AM1.5 solar spectrum through InAlAsP window layer. The simulation and optimization at 300K of short circuit current parameters (Jsc), open circuit voltage (Voc), fill factor (FF) and efficiency (?) are done using Tcad Silvaco software. The characteristics obtained are: the minimized thickness of 665 nm, electrical efficiency is about ? = 21.87% for InGaP cell, Jsc = 14.43 mA/cm2, Voc = 1.63 V, and FF = 91.21 %.

Novel buffer layer on the performance of CZTS solar cells by numerical simulation

Cu2ZnSnS4 as the promising absorber layer material, has received great attention in the application of highly efficient and low-cost thin film solar cells. The theoretical photovoltaic conversion efficiency of the CZTS thin-film solar cells reaches up to around 32%. Conventionally, CdS or CdSe have been used as buffer layers in these cells. However, cadmium's toxicity and volatility pose environmental concerns. This paper explores TiNxOy and CrNxOy as buffer layers in CZTS solar cells, investigated through numerical simulations using SCAPS-1D. Thickness and carrier concentration on the solar cell performance are mainly investigated. Effects of conduction band offset and defect density on photovoltaic parameters of CZTS/TiNxOy and CZTS/CrNxOy solar cells are also simulated based on the optimal thickness and carrier concentration. The simulation results point out that the photovoltaic conversion efficiency of both systems achieves 22% when TiNxOy or CrNxOy is used as buffer layers. Notably, compared with the CZTS/CrNxOy solar cell structure, TiNxOy as the buffer layer provides a more compatible band offset with the CZTS layer.

Optimisation and numerical analysis of highly efficient CGSe-based thin film solar cell

Among the various chalcopyrites compounds used in photovoltaic devices, Copper Gallium Selenium (CGSe) turns out as an underperformer due to its limited photovoltaic performance, So far highest efficiency measured is about 11.9%. This paper investigates the possibilities for efficiency enhancement for the CuGSe layer in Cu2O/CGSe/TiO2/ZnO thin film solar cell structure using the SCAPS-1D simulation program. The short circuit current (Jsc) and power conversion efficiency (PCE) is 30.77 mA cm−2 and 27.10%, with open-circuit voltage (Voc) and fill factor (FF) of 1.03 V and 84.72% respectively. Furthermore, we evaluated some specific parameters of TiO2/CGSe heterostructure, such as the influence of layer thickness, operating temperature, the effect of defect density and acceptor density of CGSe layer, metal work function, and the effect of series and shunt resistance on cell performance. We investigated that combining TiO2 as an ETL and Cu2O as HTL with a CGSe absorber layer is novel and promising, which results in higher power conversation efficiency and improves other PV parameters. The application of CGSe/TiO2 heterojunction in a simulated model offers a viable method for the development of high-efficiency solar cell devices.

Computational analysis on the role of an AGT current enhancer in a CZTS-based thin film solar cell

This paper gives a synopsis of a CZTS-based n-CdS/p-CZTS/p + -AgGaTe2/p++-MoS2 thin film solar cell that has been designed and explored by the simulation technique with the help of a solar cell capacitance simulator (SCAPS-1D). The design utilizes CdS as the window layer, CZTS as the first absorber layer, AgGaTe2 as the second absorber layer, and MoS2 as the BSF layer. The influencing parameters of these materials such as thickness, doping concentration, and defect density have been adjusted to achieve the right balance between the proposed structure and to see the changes that affect the device's overall performance. In ideal condition, the single n-CdS/p-CZTS heterojunction structure shows power conversion efficiency (PCE) of 17.75% with short circuit current, JSC of 24.82 mA/cm2, open circuit voltage, VOC of 0.88 V and fill factor (FF) of 81.3%. But, with the inclusion of MoS2 as the BSF, the overall PCE is elevated to 25.84% with VOC of 1.09 V, JSC of 26.96 mA/cm2 and FF of 87.64%. Finally, with the fusion of AgGaTe2 as a current augmenting layer the JSC gets a huge boost and is enhanced to 34.7 mA/cm2 with a PCE of 33.89%. These simulation findings unveil the potential of the proposed solar cell structure with CZTS as the absorber layer and AgGaTe2 as the current boosting layer in creating an environment-friendly, affordable and highly efficient thin film solar cell.

Design and performance evaluation of all-inorganic AgTaS3 perovskite solar cells

Narrow bandgap AgTaS3 perovskite can offer highly efficient thin film solar cells (SCs) and become Si counterparts that are leading in the market.

Multi-layer transparent electrodes for high performance bifacial perovskite solar cells

Bifacial perovskite solar cells have gained significant interest due to their high light-harvesting capabilities. In this study, a multilayer transparent conducting film (MLTCF) composed of indium tin oxide (ITO)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/Ag/ITO is developed as a top electrode for bifacial perovskite solar cells (PSCs). By applying BCP at the bottom of the ITO layer as an adhesion promoter, the Volmer–Weber mechanism of island growth pattern for Ag under thickness threshold conditions is successfully suppressed. This results in ultra-thin (8 nm) and ultra-smooth Ag films with a relatively low sheet resistance of 5.5 Ω/sq and high transmittance of 85.8 % at a typical wavelength of 550 nm. Furthermore, a molybdenum oxide (MoO3) overlayer is evaporated onto the soft organic charge transport layer as a protective buffer to prevent sputtering damage during the deposition of ITO and Ag films. Consequently, bifacial PSCs exhibit an optimized power conversion efficiency (PCE) of 20.3% for single-side illumination from the glass side, and equivalent PCEs of 23.6 %, 25.2 %, 26.8 % with albedo of 0.2, 0.3 and 0.4, respectively. This work paves the way for the development of highly efficient bifacial thin-film solar cells.

Grain Engineering of Sb2 S3 Thin Films to Enable Efficient Planar Solar Cells with High Open-Circuit Voltage.

Sb2 S3 is a promising environmentally friendly semiconductor for high performance solar cells. But, like many other polycrystalline materials, Sb2 S3 is limited by nonradiative recombination and carrier scattering by grain boundaries (GBs). This work shows how the GB density in Sb2 S3 films can be significantly reduced from 1068±40to 327±23nm µm-2 by incorporating an appropriate amount of Ce3+ into the precursor solution for Sb2 S3 deposition. Through extensive characterization of structural, morphological, and optoelectronic properties, complemented with computations, it is revealed that a critical factor is the formation of an ultrathin Ce2 S3 layer at the CdS/Sb2 S3 interface, which can reduce the interfacial energy and increase the adhesion work between Sb2 S3 and the substrate to encourage heterogeneous nucleation of Sb2 S3 , as well as promote lateral grain growth. Through reductions in nonradiative recombination at GBs and/or the CdS/Sb2 S3 heterointerface, as well as improved charge-carrier transport properties at the heterojunction, this work achieves high performance Sb2 S3 solar cells with a power conversion efficiency reaching 7.66%. An impressive open-circuit voltage (VOC ) of 796mV is achieved, which is the highest reported thus far for Sb2 S3 solar cells. This work provides a strategy to simultaneously regulate the nucleation and growth of Sb2 S3 absorber films for enhanced device performance.

Effects of ZnSO4 concentration on the high-rate deposition of CBD-Zn(O,S) buffer layer for Cu(In,Ga)Se2 thin-film solar cells

To utilize eco-friendly materials in Cu(In,Ga)Se2 (CIGS) thin-film solar cells, a Zn-based buffer layer has been adopted to replace the conventional CdS buffer layer. Buffer layers can be grown using a variety of techniques, with chemical bath deposition (CBD) generally used for the preparation of the Zn(O,S) buffer layer. The growth rate of the CBD-Zn(O,S) buffer layer is determined by the dissociation rate of S during chemical reaction between Zn and S ions. Thiourea (TU) is a conventional precursor of S, but it suffers from poor dissociation rate of S, leading to prolonged layer deposition times. In this study, we replaced TU with thioacetamide (TAA), thereby drastically shortening the deposition time from 80 min (TU) to 7 min (TAA). Furthermore, incorporating Zn with S ions is known to be difficult owing to the high-speed release of S ions from TAA. However, by adjusting the molar concentration of ZnSO4, we discovered a process to effectively form the Zn–S bonds for the CBD-Zn(O,S) buffer layer. The efficiency of the CIGS thin-film solar cell shows the best performance at a ZnSO4 concentration of 0.05 M, which rivals the performance of the TU base process. The physical and chemical properties of CBD-Zn(O,S) grown at a high deposition rate using TAA were examined as a function of ZnSO4 molar concentration. We proposed a growth model that accounts for the changes in film thickness and surface morphology evolution, both of which depend on the ZnSO4 concentration. Additionally, to investigate the p–n junction properties in terms of device operation, we elucidated the band alignment at the CIGS/CBD-Zn(O,S) interface, concentrating on the interfacial barrier height. It is empirically demonstrated that a lower ΔEC value improves the solar cell operation.