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Tin sulfide (SnS) absorbers have received considerable attention for their application in highly efficient, inexpensive, and stable thin-film solar cell (TFSC) technology. The present study reports the performance enhancement in the SnS-based TFSC by incorporating an antimony sulfide (Sb2S3) as a hole transport layer (HTL) between the absorber and rear electrode. The SCAPS-1D (solar cell capacitance simulator in one dimension) was utilized to modify the conventional SnS solar cell and to investigate the performance parameters of the proposed heterojunction nickel (Ni)/antimony sulfide (Sb2S3)/SnS/cadmium sulfide (CdS)/fluorine-doped tin oxide (FTO)/aluminum (Al) solar device. Different HTLs including Sb2S3, copper iodide (CuI), and nickel oxide (NiOx) were investigated to determine the most effective HTL for SnS solar cells. The performance of the proposed TFSC was also examined by varying the thickness, carrier concentration, bulk defect density, temperature, metal work function, and cell resistance. Power conversion efficiency of 30.47% with open-circuit voltage (Voc) of 1.02 V, short-circuit current density (Jsc) of 34.34 mA/cm2, and fill factor (FF) of 87.25% were achieved for the optimized heterojunction SnS cell structure. These findings suggest that the low-toxicity Sb2S3 can be effectively employed as an HTL in highly efficient and low-cost SnS TFSCs. [ABSTRACT FROM AUTHOR]

This paper examines the effect of temperature variation on the surface triangular grating of the surface plasmon polariton (SPP) on the effectiveness of the entire array of silicon thin-film solar cells. Thin-film solar cells' optical and electrical characteristics are examined using the electromagnetic and semiconductor models. The 3D Multiphysics simulator is used to present this study. The MATLAB/SIMULINK model based on mathematical formulas is developed to simulate the entire array of solar cells with thin films. This approach is suggested for quickly simulating the thin-film array. The presented model was applied on thin-film solar cells with and without SPP depending on the complete cell parameters from the COMSOL Multiphysics model. The triangle's SPPs accomplish a 14.76% efficiency increase of 1.07% over a solar cell without SPPs. [ABSTRACT FROM AUTHOR]

In this study, a CIGS solar cell with a Mo/Cu(In0.7Ga0.3)Se2(CIGS)/CdS/ZnO/Al-doped ZnO (AZO) structure was simulated by Atlas silvaco-TCAD software. The photovoltaic characteristics of solar cells using CdS and ZnSe buffer layers were calculated and compared. Then, the photovoltaic characteristics were examined with different thicknesses of the ZnSe buffer layer. The 25 nm thickness was selected as the optimum thickness. After optimization of the ZnSe layer thickness, the photovoltaic characteristics of solar cells were evaluated by changing the conduction band offset (CBO). The highest CIGS solar cell conversion efficiency was obtained in the range from -0.5 eV to +0.5 eV for CBO. Finally, graphene was replaced with Al-doped ZnO (AZO) due to its high optical transparency, high carrier mobility, and proper mechanical properties. Graphene was used as a monolayer and multilayer as a transparent conductive oxide (TCO) layer. Simulations predicted the highest efficiency for solar cell structure based on Mo/CIGS/ZnSe/i-ZnO/monolayer graphene and the photovoltaic parameters were Jsc=38.64 mA/cm², Voc=0.67 V, FF=79.33% and η=20.71%. [ABSTRACT FROM AUTHOR]

Abstract In this study, the SCAPS-1D tool has been used to numerically examine the performance of Transition Metal Dichalcogenides (TMDC) based Molybdenum ditelluride (MoTe2) solar cells containing CdS electron transport layer (ETL) and Cu2O hole transport layer (HTL). Based on the photovoltaic cell parameters, including absorber layer thickness, temperature, defect density, the effects of series and shunt resistance, and electron affinity, the structure of both MoTe2 based solar cells with and without the usage of the HTL has been analyzed. With 1.1 μm thickness of MoTe2 and doping density of 5 × 1015 cm−3, Al/FTO/CdS/MoTe2/Cu2O/Ni heterojunction’s solar cell proposed structure has been optimized. The final power conversion efficiency (PCE) = 32.38%, open-circuit voltage (Voc) = 1.07 V, short-circuit current (Jsc) = 35.12 mA/cm2, and fill factor (FF) = 86.32% has been determined from the optimized structure. The determined results indicate a suitable path for the realization of low cost and high efficiency MoTe2-based solar cell.

Conventional Copper Indium Gallium Di Selenide (CIGS)-based solar cells are more efficient than second-generation technology based on hydrogenated amorphous silicon (a-Si: H) or cadmium telluride (CdTe). So, herein the photovoltaic (PV) performance of CIGS-based solar cells has been investigated numerically using SCAPS-1D solar simulator with different buffer layer and less expensive tin sulfide (Sn2S3) back-surface field (BSF). At first, three buffer layer such as cadmium sulfide (CdS), zinc selenide (ZnSe) and indium-doped zinc sulfide ZnS:In have been simulated with CIGS absorber without BSF due to optimized and non-toxic buffer. Then the optimized structure of Al/FTO/ZnS:In/CIGS/Ni is modified to become Al/FTO/ZnS:In/CIGS/Sn2S3/Ni by adding a Sn2S3 BSF to enhanced efficiency. The detailed analysis have been investigated is the influence of physical properties of each absorber and buffer on photovoltaic parameters including layer thickness, carrier doping concentration, bulk defect density, interface defect density. This study emphasizes investigating the reasons for the actual devices' poor performance and illustrates how each device's might vary open-circuit voltage (VOC), short-circuit current density (JSC), fill factor (FF), power conversion efficiency (PCE), and quantum efficiency (QE). The optimized structure offers outstanding power conversion efficiency (PCE) of 21.83 % with only 0.80 μm thick CIGS absorber. The proposed CIGS-based solar cell performs better than the previously reported conventional designs while also reducing CIGS thickness and cost.

In this study, the SCAPS-1D tool has been used to numerically examine the performance of Transition Metal Dichalcogenides (TMDC) based Molybdenum ditelluride (MoTe2) solar cells containing CdS electron transport layer (ETL) and Cu2O hole transport layer (HTL). Based on the photovoltaic cell parameters, including absorber layer thickness, temperature, defect density, the effects of series and shunt resistance, and electron affinity, the structure of both MoTe2 based solar cells with and without the usage of the HTL has been analyzed. With 1.1 μm thickness of MoTe2 and doping density of 5 × 1015 cm−3, Al/FTO/CdS/MoTe2/Cu2O/Ni heterojunction's solar cell proposed structure has been optimized. The final power conversion efficiency (PCE) = 32.38%, open-circuit voltage (Voc) = 1.07 V, short-circuit current (Jsc) = 35.12 mA/cm2, and fill factor (FF) = 86.32% has been determined from the optimized structure. The determined results indicate a suitable path for the realization of low cost and high efficiency MoTe2-based solar cell. [ABSTRACT FROM AUTHOR]

Thin-film photovoltaics based on earth-abundant and non-toxic Sb2S3 is the frontrunner material in thin-film solar cells due to its broad-band optical response and excellent electrical properties. Nevertheless, a PCE of ~ 28.64% has been projected for Sb2S3 solar cells, and the highest reported efficiency is ~ 8%. The poor performance of Sb2S3-based solar cells is attributed to deep intrinsic traps that enhance recombination. Due to lattice dislocations, surface defects lead to sluggish charge transfer across interfaces and poor charge carrier mobility. A better understanding of the recombination losses in Sb2S3 bulk as an intrinsic layer and interfaces of Sb2S3/electron transport and Sb2S3/hole transport layers and transport mechanisms could lead to significant advancements in device performance. This review discusses the limitations of Sb2S3-based solar cells based on theoretical and experimental studies, which will pave the way for future improvements in Sb2S3-based solar cells. [ABSTRACT FROM AUTHOR]

Smooth and compact Cu(In, Ga)Se2 (CIGSe) thin film is critical to prepare high-quality solar cells. However, the ”dendritic” morphology of Cu tends to form on Mo leading to a nonuniform Cu distribution during the electrodeposition process, which affects the uniformity of CIGSe and device performance. In this work, Ag was used as the underlying buffer layer and Cu was electrodeposited on Ag film instead of Mo film. By adjusting deposition parameters, smooth and compact Ag layer was obtained on the Mo surface. With the Ag buffer layer, the ”dendritic” Cu on Mo was successfully eliminated. The electrodeposited Ag/Cu/In/Ga metal precursors were annealed in Se-containing atmosphere at 450 °C∼550 °C for 15min to prepare (Ag, Cu)(In, Ga)Se2 (ACIGSe) absorbers. Compared with the CIGSe absorber, the crystallinity of the ACIGSe absorber was improved. The VOC, JSC, FF and efficiency of ACIGSe solar cells were improved compared with CIGSe solar cells. Ultimately, an 11.73% efficiency of ACIGSe thin-film solar cells was obtained.

Due to the advantages of abundant earth elements, low toxicity and environment protection, Cu2ZnSn (S,Se) 4 (CZTSSe) thin-film solar cells are thought to be suitable for the large-scale production in the future. At present, the efficiency of these devices is always limited by the high cation disorder of the absorber layer and the low open-circuit voltage of the device. To solve this problem, the cation doping measure has been proposed by scientists, which is the disorder of cations can be reduced by introducing other cations, improving the photoelectric conversion efficiency of the device. It has also been proved that cation doping is great significant in improving the performance of devices. Based on this, the research progress of cation doping measures in optimizing the performance of CZTSSe devices is discussed in detail, including the additional addition of cations (e g, Na, K, Sb) and cation substitution (e g, substitution of Cu, Zn, and Sn with Li/Ag, Mn/Mg/Ba/Cd, and Ge, respectively) . It is concluded that the most promising cations are Cd2+ and Ge4+ ions, considering the toxicity of Cd, Ge should be the most promising element in optimizing the performance of CZTSSe devices. [ABSTRACT FROM AUTHOR]

This paper introduces and numerically analyzes flower-shaped nanowires (FS-NWs) with improved light harvesting. The optical and electrical characteristics are studied using the finite-difference time-domain and finite-element methods. In this study, the ultimate efficiency (η), optical generation (G), short circuit current density (JSC), open-circuit voltage (Voc), and electrical power conversion efficiency (PCE) are numerically computed. The geometrical parameters of the suggested FS-NWs are tuned to improve the optical absorption and hence the ultimate efficiency. The FS-NWs show higher absorption than the conventional cylindrical NWs (CC-NWs) due to the multiple resonance peaks and higher cross-section scattering in the high photon energy band. The reported FS-NWs provide an optical efficiency (η) of 35.6%, with an improvement of 11.4% over CC-NWs. This is due to the capability of the FS-NWs to trap more photons and generate more supported modes through the active absorbing layer. The reported design with axial doping junction offers an open-circuit voltage (Voc) of 0.68 V, short circuit current density (JSC) of 18.68 mA/cm2, and PCE of 9.6%, which are better than that of CC-NWs with Voc of 0.70 V, JSC of 17.88 mA/cm2, and PCE of 8.68%. [ABSTRACT FROM AUTHOR]

The Zn(O,S) thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se2 (CIGS) thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap. In this paper, the thin-film growth mechanism and process optimization of Zn(O,S) films fabricated using the chemical bath deposition method are systematically investigated. The thickness and quality of Zn(O,S) films were found to be strongly affected by the concentration variation of the precursor chemicals. It was also revealed that different surface morphologies of Zn(O,S) films would appear if the reaction time were changed and, subsequently, the optimum reaction time was defined. The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high. In addition, to further improve the film quality, an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S) thin film was improved by an ammonia etching process followed by an annealing process. For comparison purposes, both Zn(O,S)-based and CdS-based devices were fabricated and characterized. The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell. [ABSTRACT FROM AUTHOR]

In this work, we have experimentally investigated the impact of light trapping on the performance of InAs/GaAs quantum dot (QD) solar cells. To increase the amount of absorbed near-infrared photons, we fabricated a thin-film QD solar cell with a backside mirror where the positions of the QD layers were matched with the intensity peaks of one of the Fabry–Perot (FP) resonances in this structure to enable enhanced QD absorption near 1192 nm. We demonstrate that the external quantum efficiency at a given FP resonance wavelength of such an InAs/GaAs-based QD solar cell can be increased by an order of magnitude over solar cells without FP resonance by optimally positioning the QD layers.

In recent years, plasmonics has been widely employed to improve light trapping in solar cells. Silver nanospheres have been used in several research works to improve the capability of solar absorption. In this paper, we use silver pyramid-shaped nanoparticles, a noble plasmonic nanoparticle, inside thin-film silicon and InP solar cells to increase light absorption compared to previously published topologies. The proposed structure consists of a TiO2 pyramid structure placed at the top of the surface working as an anti-reflective layer, silicon/indium phosphate as an absorption layer, silver pyramid-shaped nanoparticles incorporated inside the absorption layer, and an aluminum reflecting layer at the bottom. In this research, we used finite difference time domain (FDTD) simulation to model the thin-film solar cell (TFSC). Optimizing the shape and placement of the silver pyramids, we have achieved an efficiency of 17.08% and 18.58% using silicon and InP as the absorbing layers respectively, which is significantly better than previously reported studies. The open-circuit voltages are 0.58 V and 0.92 V respectively, which is the highest among other configurations. To conclude, the findings of this study laid the foundation to create an efficient thin-film solar cell utilizing the light-trapping mechanism of noble plasmonic nanoparticles.

We report on the chemical and electronic structure of the interface between a thermally co-evaporated InxSy buffer and a Cu2ZnSn(S,Se)4 (CZTSSe) absorber for thin-film solar cells. To date, such cells have achieved energy conversion efficiencies up to 8.6%. Using surface-sensitive X-ray and UV photoelectron spectroscopy, combined with inverse photoemission and bulk-sensitive soft X-ray emission spectroscopy, we find a complex character of the buffer layer. It includes oxygen, as well as selenium and copper that diffused from the absorber into the InxSy buffer, exhibits an electronic band gap of 2.50 ± 0.18 eV at the surface, and leads to a small cliff in the conduction band alignment at the InxSy/CZTSSe interface. After an efficiency-increasing annealing step at 180 °C in nitrogen atmosphere, additional selenium diffusion leads to a reduced band gap at the buffer layer surface (2.28 ± 0.18 eV).

We report on the chemical and electronic structure of the interface between a thermally co-evaporated InxSy buffer and a Cu2ZnSn(S,Se)4 (CZTSSe) absorber for thin-film solar cells. To date, such cells have achieved energy conversion efficiencies up to 8.6%. Using surface-sensitive X-ray and UV photoelectron spectroscopy, combined with inverse photoemission and bulk-sensitive soft X-ray emission spectroscopy, we find a complex character of the buffer layer. It includes oxygen, as well as selenium and copper that diffused from the absorber into the InxSy buffer, exhibits an electronic band gap of 2.50 ± 0.18 eV at the surface, and leads to a small cliff in the conduction band alignment at the InxSy/CZTSSe interface. After an efficiency-increasing annealing step at 180 °C in nitrogen atmosphere, additional selenium diffusion leads to a reduced band gap at the buffer layer surface (2.28 ± 0.18 eV).

Although many environmentally friendly and non-toxic materials have been investigated for photovoltaic conversion (PVC) applications, Sb2S3 is the material of choice as an absorber in thin-film solar cells due to its broad-band optical response and excellent electrical properties. Though an Sb2S3 thin-film was predicted to have a 28% efficiency, the reported efficiency of 7% is significantly lower than the theoretically predicted efficiency and less competitive compared to other similar thin-film solar cells. This review investigates how structural and morphological changes in Sb2S3 thin films contribute to the current state of Sb2S3 solar cell development to understand and improve current device performance. We first discuss the fundamental structure and properties of Sb2S3 and then show how morphology and structural changes in Sb2S3 thin films produced using various fabrication techniques and conditions affect solar cell performance. This research includes several significant recent developments and current research trends that will pave the way for future improvements in the performance of Sb2S3-based photovoltaic solar cells.

In this article, the thin-film solar cell (TFSC) based on a non-toxic In2Se3 buffer layer and low-cost ultra-thin BaSi2 Back Surface Field (BSF) has been proposed to enhance the performance of copper indium gallium diselenide (CIGS) solar cell. The proposed AI/SnO2/In2Se3/CIGS/BaSi2/Mo TFSC also aims to be cost-effective with reduced use of toxic material. Consequently, the CIGS layer thickness has been optimized (varied from 0.1–1 μm) and the non-toxic In2Se3 buffer layer has been used compared to conventional toxic CdS-based AI/ZnO/CdS/CIGS/Mo TFSC. The proposed TFSC achieves the conversion efficiency (CE) of 28.15% for the optimized CIGS thickness of 0.7 μm and BaSi2 BSF layer thickness of 0.3 μm. Further, the proposed TFSC has been investigated for variation in defect density, acceptor impurity of the CIGS absorber layer, and operating temperature of the device. Additionally, the results obtained for the proposed TFSC show improvement in the performance from the previously reported TFSC. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS 2)-based photovoltaic cells are increasingly attracting researchers' due to their outstanding semiconducting properties. Single junction MoS 2 based solar cell have been investigated with three distinct electron transport layer (ETL) layers made of SnS 2 , In 2 S 3 and ZnSe in detail with and without back surface field (BSF). A thorough numerical analysis has been conducted of the effects of band alignment, defect density, absorber layer thickness, buffer layer thickness, interface defect density, electron and hole concentration, generation and recombination, open circuit voltage (V OC), short circuit current (J SC), fill factor (FF), and power conversion efficiency (PCE) via SCAPS-1D simulation software. The MoS 2 based solar cell produced the photo conversion efficiency (PCE) of 24.77 % with V OC of 0.913 V, J SC of 31.274 mA/cm2, and FF of 86.77 % without BSF. On the other hand, after in depth analysis, according to simulation results, SnS 2 ETL produced the highest PCE of 35.60 % than ZnSe(33.56 %) and In 2 S 3 (34.94 %) ETL with V OC of 1.07 V, J SC of 37.55 mA/cm2, and FF of 88.80 % with inserting only 30 nm V 2 O 5 BSF layer. The suggested research might provide information and a workable strategy for producing a MoS 2 -based thin-film solar cell that is affordable. • Single junction MoS 2 based solar cell have been investigated with three distinct ETL layers (SnS 2 , In 2 S 3 , ZnSe) via SCAPS-1D. • Impact of V 2 O 5 back surface field on MoS 2 based solar cell have been explored in detail via SCAPS-1D. • The MoS 2 based solar cell have shown highest PCE of 35.60 % with SnS 2 ETL and V 2 O 5 BSF. [ABSTRACT FROM AUTHOR]

In photovoltaic (PV) solar cells, the photo-absorbing structure should absorb solar energy optimally to convert it into electrical power efficiently. The major criteria for sustainable PV technology are using low-cost photo-absorbing material and thin-film structures with efficient optical and electrical performances. We propose a monomer and trimer array-based heterogeneous nanopillar (MTHN) structure for efficient light absorption inspired by Chlamydomonas reinhardtii. We have designed low-cost earth-abundant crystalline silicon (cSi)-based single-junction thin-film PV solar cells utilizing the MTHN structure. The proposed structure shows absorption characteristics insensitive to the incident light's polarization, and an optimized MTHN structure's light absorption efficiency (LAE) is 94%. We calculated the power conversion efficiency (η PCE) with different nanopillar heights (h np) to analyze the effect on optical and electrical performances. We also investigated the impact of bulk doping concentration (p) on the open circuit voltage (V oc), short circuit current density (J sc), and η PCE. The value of η PCE reaches 16.14% using the MTHN structure, which is the maximum value for cSi-based single-junction thin-film PV solar cells in the wavelength range of 400 to 1000 nm. • A light absorption structure inspired by Chlamydomonas reinhardtii is proposed. • Absorption is insensitive to the incident light's polarization with ¿94% efficiency. • Efficiency exceeds c-Si single-junction solar cells available in the literature. [ABSTRACT FROM AUTHOR]

[Display omitted] • There is a special structural combination in this solar cell. • The extremely thin wall of the structure will reduce manufacturing costs. • Using V 2 O 5 HTL, the maximum PCE was reached at 35.13% with a V OC of 1.0738 V, a J SC of 36.8308 mAcm-2, and an FF of 88.83%. • This configuration will be very helpful in evaluating future generation solar cells. Researchers are becoming more interested in molybdenum disulfide (MoS 2)-based photovoltaic cells because of their exceptional semiconducting qualities. The use of CdS ETL and V 2 O 5 HTL in thin-film solar cells based on MoS 2 has been studied. The effects of electron and hole concentration, generation and recombination, FF, V OC , J SC , band alignment, defect density, absorber layer thickness, buffer layer thickness, interface defect density, and PCE have all been thoroughly numerically analyzed. The SCAPS-1D simulation software was applied to conduct the aforementioned investigation. The study found that the V 2 O 5 HTL design reached the maximum PCE at 35.13 % with a V OC of 1.0738 V, a J SC of 36.8308 mAcm−2, and a FF of 88.83 %. On the other hand, without HTL configuration, the PCE was 23.05 %, the V OC was 0.9049 V, the J SC was 29.4614 mAcm−2, and the FF was 86.45 %. These findings offer useful data and a practical plan for developing inexpensive, MoS 2 -based thin-film solar cells. [ABSTRACT FROM AUTHOR]

In this research, the influences of Na doping content on the microstructure of CIGS absorption layer and the electrical performance of CIGS solar cell are investigated. It is found that Na is benefit to reducing the thickness of MoSe2 layer which is between the CIGS absorption layer and Mo back contact layer, and decreasing the series resistance and improving the fill-factor of the cell. Besides, Na will influence the distribution of Ga. With the increase of the Na doping, Ga elements tend to accumulate at the back region of the CIGS absorption layer, and form a strong back surface field which reduces the carriers recombination. Those effects contribute to the improvement of the CIGS cells efficiency. [ABSTRACT FROM AUTHOR]

This paper discusses the impact of the p-MoS2 transition metal dichalcogenide as an interfacial layer between the CZTS absorber and Mo back contact in the CZTS based solar cell. The study was performed using SCAPS-1D numerical simulation. The I–V characteristic demonstrated a higher slope than CZTS solar cells without considering the interfacial layer. The results verified that the p-MoS2 layer beneficially on the CZTS/Mo hetero-contact mediating an ohmic contact. Accordingly, the conversion efficiency improves from 12.14% to 16.71%. To evaluate the role of the p-MoS2 layer, various performance parameters such as open-circuit voltage (Voc), short circuit current (Jsc), fill factor FF, and efficiency η were explored versus thicknesses, bandgap energies, and the acceptor carrier concentration (NA). The results show that a thickness of the interfacial layer of less than 200 nm could cause deterioration of the overall cell performance, mainly due to created high barriers at the CZTS/p-MoS2 and p-MoS2/Mo interfaces, at low thicknesses, which impedes the drift of photogenerated holes. Additionally, increasing the NA above 1016 cm−3 improves the cell performance, owing to the favourable band alignment at the back contact. Values obtained for Voc and Jsc are 0.88 V and 25.5 mA/cm2, respectively. Moreover, the effect of series resistance Rs on CZTS solar cells was investigated. The efficiency decreases from 12.84% to 9.69% when the Rs correspondingly increases from 0 Ω to 5 Ω. [ABSTRACT FROM AUTHOR]

In the last few years the need and demand for utilizing clean energy resources has increased dramatically. Energy received from sun in the form of light is a sustainable, reliable and renewable energy resource. This light energy can be transformed into electricity using solar cells (SCs). Silicon was early used and still as first material for SCs fabrication. Thin film SCs are called as second generation of SC fabrication technology. Amorphous silicon (a-Si) thin film solar cell has gained considerable attention in photovoltaic research because of its ability to produce electricity at low cost. Also in the fabrication of a-Si SC less amount of Si is required. In this review article we have studied about types of a-Si SC namely hydrogenated amorphous silicon (a-Si:H) SC and hydrogenated amorphous silicon germanium(a-SiGe:H) SC. This article also reviews about various techniques adopted to improve the efficiency and performance of a-Si SC, stability issues in a-Si SC as well its recent developments. [ABSTRACT FROM AUTHOR]

CdS/Cu2ZnSnS4 (CZTS) heterojunction thin-film solar cells were fabricated via a closed tube sulfurization under saturated sulfur vapor pressure. A significant improvement in the crystalline quality of the CZTS polycrystalline thin-film was achieved when the Cuâ€"Znâ€"Sn metallic-alloy thin-film was sulfurized under saturated sulfur vapor pressure of 4.3 atm at 590 °C due to efficient suppression of re-evaporation of Zn and Sn species during the growth process. Accordingly, the open-circuit voltage and short-circuit current density of the CdS/CZTS heterojunction device were enhanced resulting in the improvement of power conversion efficiency by over 1.7 times compared to the best cell fabricated by the conventional processes under unsaturated sulfur vapor pressure of 1.5 atm. [ABSTRACT FROM AUTHOR]

Abstract In this study, copper bismuth oxide (CuBi2O4) absorber-based thin film heterojunction solar cell structure consisting of Al/FTO/CdS/CuBi2O4/Ni has been proposed. The proposed solar cell device structure has been modeled and analyzed by using the solar cell capacitance simulator in one dimension (SCAPS-1D) software program. The performance of the proposed photovoltaic device is evaluated numerically by varying thickness, doping concentrations, defect density, operating temperature, back metal contact work function, series and shunt resistances. The current density–voltage behaviors at dark and under illumination are investigated. To realize the high efficiency CuBi2O4-based solar cell, the thickness, acceptor and donor densities, defect densities of different layers have been optimized. The present work reveals that the power conversion efficiency can be enhanced by increasing the absorber layer thickness. The efficiency of 26.0% with open-circuit voltage of 0.97 V, short-circuit current density of 31.61 mA/cm2, and fill-factor of 84.58% is achieved for the proposed solar cell at the optimum 2.0-μm-thick CuBi2O4 absorber layer. It is suggested that the p-type CuBi2O4 material proposed in the present study can be employed as a promising absorber layer for applications in the low cost and high efficiency thin-film solar cells.

Polycrystalline Cu(In,Ga)Se 2 (CIGS) solar cells are widely studied for their application in thin-film photovoltaics, but analysis of their crystalline properties is difficult owing to the presence of grain boundaries and defects. Epitaxial CIGS (epi-CIGS) solar cells can potentially address the issues of polycrystalline CIGS (poly-CIGS) solar cells, but their conversion efficiency has not been widely studied. We fabricated epi-CIGS layers using techniques developed for high-efficiency ploy-CIGS solar cells such as Ga grading, Na doping, and heat-light soaking. Here, scanning transmission electron microscopy and secondary ion mass spectrometry were used to compare the structural characteristics of poly- and epi-CIGS solar cells with conversion efficiencies of more than 21%. Both types of solar cells had similar Ga gradient profiles, and abrupt interfaces were observed between the CIGS and Mo, CIGS and GaAs, and CdS and CIGS layers. The poly-CIGS layer had a higher Na concentration than the epi-CIGS layer because the grain boundaries of the former included high concentrations of Na ions. Meanwhile, the Na ions in the epi-CIGS layer promoted the interdiffusion of In and Ga. For both types of solar cells, heat-light soaking increased the carrier concentration by more than 1 × 1017 cm−3. These observations suggest that grain boundaries are not the main factor limiting the conversion efficiency of poly-CIGS solar cells. • Structural properties of polycrystalline and epitaxial CIGS solar cells are compared. • Lattice patterns with no dislocation at CdS/CIGS and CIGS/GaAs are confirmed. • The epi-CIGS solar cell achieved a maximum conversion efficiency of 21.3%. [ABSTRACT FROM AUTHOR]

The photovoltaic (PV) market today is dominated by silicon (Si)-based solar cells, which, however, can be improved in performance and cost by developing technologies that use less material. We propose an indium phosphide (InP) nanoresonator array on silicon ultra-thin film with a combined thickness of 0.5 μm to 2 μm as a solution to minimize cost and maximize power efficiency. This paper focuses on simultaneously achieving broadband antireflection and enhanced absorption in thin-film Si with integrated InP nanodisk arrays. Electromagnetic simulations are used to design and optimize the reflectance and absorption of the proposed design. By varying the height and radius of the InP nanodisks on the Si substrate, together with the array pitch, a weighted reflectance minimum, with respect to the AM1.5 solar spectrum, of 2.9% is obtained in the wavelength range of 400 nm to 1100 nm. The antireflective properties are found to be a combination of a Mie-resonance-induced strong forward-scattering into the structure and an effective index-matching to the Si substrate. In terms of absorption, even up to 2 μm from the Si surface the InP nanodisk/Si structure consistently shows superior performance compared to plain Si as well as a Si nanodisk/Si structure. At a depth of 500 nm from the surface of the substrate, the absorption values were found to be 47.5% for the InP nanodisk/Si structure compared to only 18.2% for a plain Si substrate. This shows that direct bandgap InP nanoresonator arrays on thin-film Si solar cells can be a novel design to enhance the absorption efficiency of the cell. [ABSTRACT FROM AUTHOR]

In this study, we developed a new facial recognition system using thin-film solar cells as sensors. When the face of a user is illuminated by LED lights on the left and right sides of the system and the reflected light enters the cells at the corresponding positions, differences in facial skin colors and 3D contours lead to different output voltages and currents of the thin-film solar cells. This is the basis of facial feature identification. We found that the accuracy of thin-film-solar-cell-based facial recognition can be improved by precisely controlling changes in LED light intensity. The facial features of six different users were successfully distinguished by this method, thus verifying that thin-film solar cells can be used for green power generation, as well as for facial recognition. [ABSTRACT FROM AUTHOR]

In this work, the temperature effects on the PV's electrical and optical parameters of different surface gratings are studied. A 3D simulation is introduced for studying the PV's electrical parameters such as short circuit current, open-circuit voltage, and efficiency at different levels of temperature with and without surface's gratings. We observed that the efficiency is increased for PV of surface grating by about 4.87% compared to the free grating surface's PV. The efficiency of the PV efficiency is degraded when the temperature is increased above 300 K. The solar cell efficiency of gratings free is aggressively degraded compared to the solar cell that includes gratings by about 4.89% at 360 K. The electrical parameters such as the open-circuit voltage and short circuit current are enhanced compared to the PV of surface grating free. Also, we observed that the triangle grating geometry of dimensions about 10 × 10 nm produced a higher efficiency compared to the other PV of other grating geometries of the same dimensions. [ABSTRACT FROM AUTHOR]

• Ag is added into polycrystalline CuGaSe 2 films applied as photovoltaic absorbers. • Ag-alloying promotes CuGaSe 2 crystallization and increases grain size. • Residual Ga 2 Se 3 phase during CuGaSe 2 growth is suppressed. • Depletion width in solar cells is enlarged, improving carrier collection. • Ag-alloyed CuGaSe 2 solar cells with conversion efficiency of 5.3% is demonstrated. Crystal growth promotion for CuGaSe 2 (CGSe) photovoltaic absorber by silver (Ag)-addition is demonstrated, enhancing device performance for wide-gap CGSe solar cells. By introducing Ag precursor, the grain size in the polycrystalline CGSe films deposited by the three-stage process is increased, and a residual Ga 2 Se 3 phase during the growth is suppressed. Photoluminescence intensity is enhanced with Ag-addition, indicating reduced non-radiative recombination, which is related to the suppression of Ga 2 Se 3 phase and reduction of undesirable deep defect levels. For the Ag-alloyed CGSe solar cells, Urbach energy defined from the sub-gap tail in exponential external quantum efficiency is monotonically reduced from 25.5 to 21.1 meV, suggesting the improvement of CGSe bulk quality by Ag-alloying. Open-circuit voltage is enhanced since carrier recombination in Ag-alloyed CGSe bulk is suppressed. Short-circuit current density is also enhanced as carrier collection efficiency is improved by widened depletion width due to the reduction of carrier concentration by Ag-alloying. On the other hand, excess Ag-addition leads to increased series resistance and deterioration of the built-in potential in the solar cells due to the reduced carrier concentration in the Ag-alloyed CGSe absorber. Finally, the conversion efficiency is maximized to 5.3% at [Ag] / ([Ag] + [Cu]) ratio of 0.07 for the Ag-alloyed CGSe solar cells. These findings will help the performance enhancement for the wide-gap CGSe solar cells. [ABSTRACT FROM AUTHOR]

CuSbS2, as a direct bandgap semiconductor, is a promising candidate for fabricating flexible thin-film solar cells due to its low grain growth temperature (300°C–450°C). Uniform and highly crystalline CuSbS2 thin films are crucial to improving device performance. However, uniform CuSbS2 is difficult to obtain during electrodeposition and post-sulfurization due to the “dendritic” deposition of Cu on Mo substrates. In this study, Sb/Cu layers were sequentially pulse electrodeposited on Mo substrates. By adjusting the pulse parameters, smooth and uniform Sb layers were prepared on Mo, and a flat Cu layer was obtained on Sb without any dendritic clusters. A two-step annealing process was employed to fabricate CuSbS2 thin films. The effects of temperature on phases and morphologies were investigated. CuSbS2 thin films with good crystallinity were obtained at 360°C. As the annealing temperature increased, the crystallinity of the films decreased. The CuSbS2 phase transformed into a Cu3SbS4 phase with the temperature increase to 400°C. Finally, a 0.90% efficient solar cell was obtained using the CuSbS2 thin films annealed at 360°C.

CZTSSe-based solar cell structures have shown remarkable properties in terms of their low cost, greater stability, high absorption coefficient, and relatively inexpensive production process. However, their maximum achieved values of power conversion efficiency remain low, close to 12.6%. This is mainly due to the problem of back surface carrier recombination. In this paper, we present the results of studies carried out using the SCAPS-1D tool to test the viability of deploying SnS (tin sulphide) and Sn2S3 (tin(IV) sulphide) materials as a back surface field (BSF) layer, due to their inherent advantage of having a similar material composition as CZTSSe. A detailed analysis is carried out on CZTSSe and BSF layer doping variation and CZTSSe/BSF interface defect density to optimize the photovoltaic (PV) performance of the devices. The results reflect an increase in the efficiency from 12.57% to 16.34% (with SnS BSF) and 17.04% (with Sn2S3 BSF). The cell with the SnS BSF delivers an open-circuit voltage (VOC) of 0.59V, a short-circuit current density (JSC) of 37.74 mA/cm2, and a fill factor (FF) of 73.36%, while the device with the Sn2S3 BSF delivers VOC of 0.59V, JSC of 37.68 mA/cm2 and FF of 76.46%. The results reported in this study could open a pathway to realize high-efficiency CZTSSe solar cell structures in the future. [ABSTRACT FROM AUTHOR]

• Device modeling of WS 2 -based solar cell with CuI HTL has been performed by SCAPS-1D. • Comparison of PV performances between FTO/CdS/WS 2 and FTO/CdS/WS 2 /CuI is provided. • Performance enhancement of WS 2 cell with HTL is obtained by reducing recombination. • Improved efficiency of 29.87% for proposed solar cell with CuI HTL is achieved. In the present work, device modeling of tungsten disulfide-based thin-film solar cell with copper iodide as hole transport layer has been performed using the Solar Cell Capacitance Simulator in One Dimension software program (SCAPS-1D). The SCAPS-1D simulator is also utilized to investigate the photovoltaic performances of tungsten disulfide (WS 2)-based solar cells. This numerical study provides a comparison of the performances between the reference WS 2 -based solar cell structure without hole transport layer (HTL) consisting of Al/FTO/CdS/WS 2 /Ni and the proposed configuration of Al/FTO/CdS/WS 2 /CuI/Ni. The influences of thickness, doping density, bulk defect density, defect density at buffer/absorber and absorber/HTL interfaces, operating temperature, series and shunt resistances, and back surface recombination velocity on the solar cell output parameters have also been analyzed. It is revealed that the carrier recombination at the back side has notable effects on the overall photovoltaic performances of the WS 2 heterojunction solar cell without HTL. The carrier recombination loss at the back surface can be reduced by incorporation of an ultra-thin 0.1 μm copper iodide (CuI) HTL into the reference WS 2 -based solar cell and thus improves the overall performances of the proposed photovoltaic device. The conversion efficiency of 22.09% has been found for the reference WS 2 solar cell without HTL. On the other hand, the efficiency of the proposed solar cell with CuI HTL has been obtained to be 29.87% at the optimized device structure. Therefore, these findings may contribute insightful approach to fabricate viable, inexpensive, and highly efficient heterojunction thin-film solar cell. [ABSTRACT FROM AUTHOR]

• The effect of MoS 2 in the CBTS solar cell is firstly systematically studied. • The p -type MoS 2 has a beneficial effect on the performance of a CBTS solar cell. • The highest efficiency of CBTS solar cell is 18.28% by simulation. Cu 2 BaSn(S,Se) 4 (CBTSSe) solar cells are emerging photovoltaic devices due to their high theoretical efficiencies of ~31%, environment-friendly and earth-abundant composition, low density of non-recombination defects, and so on. However, the record efficiency of CBTSSe solar cell is only 5.2%, showing the importance of studying their performance via numerical analysis to further enhance their practical efficiencies. In this paper, the effect of absorber and buffer layers on performances of Cu 2 BaSnS 4 (CBTS) solar cells are firstly systematically studied via the SCAPS-1D software to provide a platform for the study of the effect of MoS 2 interlayer on the performances of CBTS solar cells. The highest PCE of CBTS solar cell with a 30 nm CdS buffer layer is 11.87%. The PCE of CBTS solar cell with a 0.8 μm CBTS absorb layer is 12.51%, indicating that the CBTS solar cell is a potential low-cost solar cell due to its large optical absorption coefficient (α > 104 cm−1). The efficiency of CBTS solar cell is improved to 16.47% when the carrier concentration of CBTS is 1016 cm−3. The relationship between the performance of solar cell and the band gap, thickness, donor concentration, acceptor concentration of MoS 2 interlayer is systematically investigated on the basis of the optimized efficiency. It is found that MoS 2 interlayer plays an important role in the performance of CBTS solar cell. The p -type MoS 2 has a beneficial effect on the efficiency improvement while the n -type MoS 2 has a negative effect on the efficiency enhancement. The highest PCE of CBTS solar cell is as high as 18.28% when the thickness and the acceptor concentration of MoS 2 are 4 nm and 1019 cm−3, respectively. Our simulation result provides a promising research direction to further improve the actual efficiency of the CBTS solar cell. [ABSTRACT FROM AUTHOR]

Cadmium telluride (CdTe) thin films were synthesized by using a two-electrode electrodeposition method on a conductive glass fluorine-doped tin oxide (FTO) substrate. The structural analysis revealed that the deposited CdTe thin films have mixed-phase cubic zinc blends and hexagonal structures in as-prepared and annealed forms with pH depositions of 1.8, 2.5, and 3.5. When the deposition pH is 3.0, only a single-phase cubic structure is observed. The crystallite sizes were 6, 14, 17, and 14 nm for as-prepared and 12, 20, 23, and 19 nm heat-treated samples for corresponding pH values of 1.8, 2.5, 3.0, and 3.5, respectively. The energy bandgaps were recorded in the range 1.38–1.58 eV for as-deposited samples and 1.35–1.5eV for annealed samples for pH values of 1.8–3.5, respectively. The surface image showed that CdTe thin films uniformly covered the glass substrate while the surface morphology of CdTe changed with pH. The availability of both Cd and Te was verified by compositional analysis. The average surface roughness recorded 50.08, 52.08, and 24.00 nm for as-prepared samples and 56.46, 78.73, and 47.17 nm for heat-treated samples for the pH values of 2.5, 3.0, and 3.5, respectively. The overall result shows that the pH value of 3.0 produced a CdTe film of good quality for solar cell application. [ABSTRACT FROM AUTHOR]

The indium gallium nitride (InGaN) semiconductor alloy shows great promise for high-efficiency thin-film solar cells due to its intrinsic characteristics. However, there are major challenges in the development of high-quality p-doped and indium-rich InGaN layers to fabricate a pn or pin solar cell. This study focuses on the development of an alternative structure, not requiring p-doping, with a Schottky contact on n-type InGaN. The InGaN absorber was grown by metalorganic chemical vapor deposition and its structural, morphological and optical properties studied. Structural analysis by X-ray diffraction showed the growth of single crystal layers without phase separation. Indium compositions which vary up to around 8.3 % were confirmed by transmission measurements. The formation of V-shaped pits was observed with increased indium composition at lower growth temperatures. Schottky diodes based on InGaN with platinum metallic contacts were fabricated and their current–voltage characteristics studied in detail as a function of temperature. This analysis of the conduction mechanisms in Schottky/InGaN devices permitted in particular the extraction of the diode parameters as a function of the temperature showing a high rectification with an ideality factor of 1.15 with reverse saturation current of 6. 7 × 1 0 − 9 A at room temperature for an indium composition of 5.52 %. In addition, the analysis revealed the presence of a dual Gaussian distribution of barrier heights in a specific temperature range. Finally, the incident photon-to-electron conversion efficiency (IPCE) of the fabricated InGaN Schottky solar cells, measured using intensity-modulated photocurrent spectroscopy, reached a peak value of 51 %, which is among the highest published values for InGaN based solar cells. [ABSTRACT FROM AUTHOR]

This paper reports on the manufacturing and evaluation of a solar power sail membrane prototype for the OKEANOS project. The in-house prototype was built by the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Mechanical and electrical evaluation tests were conducted. The membrane, thin-film solar cells, reflectivity control devices were good condition after the manufacturing and handling. The improvements in the manufacturing process and design were found. The manufacturing process and design were fundamentally established. After the prototype, improvement plans for the manufacturing process and design were tried. We have a prospect of manufacturing the flight model sail and continue to the development. [ABSTRACT FROM AUTHOR]

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The photovoltaic (PV) market today is dominated by silicon (Si)-based solar cells, which, however, can be improved in performance and cost by developing technologies that use less material. We propose an indium phosphide (InP) nanoresonator array on silicon ultra-thin film with a combined thickness of 0.5 μm to 2 μm as a solution to minimize cost and maximize power efficiency. This paper focuses on simultaneously achieving broadband antireflection and enhanced absorption in thin-film Si with integrated InP nanodisk arrays. Electromagnetic simulations are used to design and optimize the reflectance and absorption of the proposed design. By varying the height and radius of the InP nanodisks on the Si substrate, together with the array pitch, a weighted reflectance minimum, with respect to the AM1.5 solar spectrum, of 2.9% is obtained in the wavelength range of 400 nm to 1100 nm. The antireflective properties are found to be a combination of a Mie-resonance-induced strong forward-scattering into the structure and an effective index-matching to the Si substrate. In terms of absorption, even up to 2 μm from the Si surface the InP nanodisk/Si structure consistently shows superior performance compared to plain Si as well as a Si nanodisk/Si structure. At a depth of 500 nm from the surface of the substrate, the absorption values were found to be 47.5% for the InP nanodisk/Si structure compared to only 18.2% for a plain Si substrate. This shows that direct bandgap InP nanoresonator arrays on thin-film Si solar cells can be a novel design to enhance the absorption efficiency of the cell.