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Herein, the 1D Solar Cell Capacitance Simulator software is used to perform numerical analysis of thin‐film solar cells with Cu2ZnSnS4, Cu2BaSnS4, Cu2FeSnS4, and Cu2MnSnS4 absorber layers. The main goal is to investigate the impact of parameters, such as absorber layer thickness, acceptor density, buffer layer, bandgap, and donor density, on the efficiency of these solar cells. The absorber layer investigation entails varying the thickness and the acceptor density to evaluate their influence on the efficiency of the solar cell. A new zinc oxide sulfide (Zn(O,S)) buffer layer is also introduced instead of the conventional cadmium sulfide (CdS) buffer layer. The Zn(O,S) bandgap and its donor density, which are investigated in terms of how they affect the efficiency of the solar cells, have been varied. The optimal values for the thickness of the absorber layer, acceptor density, and the bandgap of the buffer layer are calculated. Subsequently, the donor density is evaluated to find any potential defects that may affect the efficiency of the solar cell. These results confirm that Zn(O,S) can be utilized as a buffer layer. This study concludes that Cu2ZnSnS4, Cu2BaSnS4, and Cu2MnSnS4 absorber layers have superior efficiency in comparison with Cu2FeSnS4. [ABSTRACT FROM AUTHOR]

One of the new materials for next-generation thin film solar cells is Cu 2 ZnSnSe 4 (CZTSe). However, achieving a single-phase CZTSe compound remains a challenge. This study describes the development of Cu 2 ZnSnSe 4 thin films through the sequential deposition of stacked films of non-stoichiometric Cu 2 SnSe 3 (CTSe) and ZnSe by magnetron sputtering. The structural, morphological, and electrical properties as well as the surface chemistry of the films were investigated and compared depending on the growth sequence of the thin films. By using Raman spectroscopy and grazing incidence X-ray diffraction, the tetragonal CZTSe structure was confirmed. Scanning electron microscopy and energy-dispersive spectroscopy measurements of the morphological and compositional properties indicated large grains and dense surfaces with an elemental composition close to the desired stoichiometry in SLG\SnSe 2 \Cu\ZnSe and SLG\SnSe 2 \Cu 2 Se\ZnSe stacks. To ascertain the surface chemistry and unique characteristics of the produced films, additional X-ray photoemission spectroscopy experiments were carried out. The optimal band gap values for the absorber layers were found using conventional spectroscopy, and they ranged from 0.88 to 1.47 eV. According to the electrical measurements, all the films were p-type and have high carrier concentrations between 1016 and 1020 cm−3. Our findings demonstrate that employing a sequential deposition approach and annealing in different atmospheres can yield CZTSe absorber layers with desirable properties, overcoming the challenge of non-stoichiometric CTSe precursors. [ABSTRACT FROM AUTHOR]

In this study, the front work function WFITO and absorber layer bandgap’s influences on two solar cells structure performances, namely ITO/(p)a-Si:H/(i)a-Si:H/(n)a-Si:H/metal (single intrinsic, Sint) structure and ITO/(p)a-Si:H/(i1)a-Si:H/(i2)a-Si:H/(n)a-Si:H/metal (double intrinsic, Dint) structure, fabricated using RF-PECVD method were simulated, using AFORS-HET (Automated FOR Simulation of Heterostructures) software. Based on these simulations, the work functions (WFITO) value ought to range from 4.9 to 5.7 eV, in order to determine the optimum WFITO for high solar cell efficiency, confirmed with the J-V dark characteristic, the band diagram in thermodynamics equilibrium, build-in electric field distribution, trapped holes density, as well as the quantum efficiency. The simulation results showed the Dint structure’s external parameters (e.g., VOC,JSC, FF, Eff) are higher, compared to the Sint structure. Furthermore, the absorber (i1 and i2) layers bandgap is optimized in an effort to improve the Dint solar cell’s performance. According to the results, the Dint structure had a 10.76 % maximum efficiency (VOC = 969.8 mV, JSC = 16.03 mA/cm2, and FF = 70 %), using WFITO, i1 layer bandgap, and i2 layer bandgap of 5.7 eV, 1.82 eV, and 1.86 eV, respectively.

Complexing agents are important in the control of chemical kinetics. Thin films of tin antimony sulphide (Sn2Sb2S5) were deposited on glass substrates and the effect of different complexing agents [tri-sodium citrate (Na3C6H5O7) and tartaric acid (C4H6O6)] on their properties were investigated. X-ray diffractometry studies indicate that the films crystallized in an orthorhombic structure. Films grown with Na3C6H5O7 exhibited increased texturing and higher crystallite size (16.6–22.1 nm), while that of C4H6O6 was between 16.80 and 20.0 nm. Energy dispersive spectroscopy studies reveal that the antimony/sulfur ratio increased with an increase in the tin content in the former and decreased with an increase in the tin content in the latter. X-ray photoelectron spectroscopy studies confirmed the formation of Sn2Sb2S5 films. Scanning electron microscopy analysis shows morphological evolution from seed-like to block-like structures in Na3C6H5O7and a seed-like structure in the C4H6O6 environments. Optical spectroscopy results indicated that the films possess optical absorption coefficient (α) > 104 cm-1and a direct energy band gap that exhibited the classic Burstein-Moss shift. The energy band gap and the processing parameters fit into a quadratic model with high values of R2. The electrical properties from Hall effect studies give typical semiconductor properties of Sn2Sb2S5 in a range suitable for use in sustainable energy devices. [ABSTRACT FROM AUTHOR]

Thin films of chemical bath deposited tin antimony sulphide (Sn2Sb2S5) were tuned by varying the deposition time between 1 and 3 h, and postdeposition heat treatments. The films were grown on soda lime glass (SLG) and on molybdenum glass (Mo-SLG) substrates, respectively. The film thickness increased with deposition time up to 2 h and decreased thereafter. Structural analysis from X-ray diffractometry showed that the films were single phase. This was corroborated by X-ray photoelectron spectroscopy (XPS) analysis. Energy-dispersive spectroscopy results give antimony/sulphur (Sb/S) ratio and antimony/tin (Sb/Sn) ratio that increased with deposition time in the SLG substrates only. Optical constants extracted from optical spectroscopy measurements give optical absorption coefficient (α) > 104 cm−1, and direct energy bandgap with values in the range 1.30 to 1.48 eV. The Hall effect measurements performed on films grown on the SLG substrates indicated that the films were p-type electrical conductivity with electrical resistivity in the range 103 to 104 Ωcm. The films grown on the Mo-SLG served as absorber layers to fabricate thin film heterojunction solar cell devices in the substrate configuration with a cadmium sulphide (CdS) window partner. The best device yielded a short-circuit current density of 20 mA/cm2, open-circuit voltage of 0.012 V and a solar conversion efficiency of 0.04%. [ABSTRACT FROM AUTHOR]

We demonstrated the solution-processed CuIn(S,Se)2 solar cells using a diamine/dithiol cosolvent. Compared to the traditional CIGS materials made with the Selenization process, we fabricated CISSe films without the Selenization process. The crystallinity, optical properties, and morphology of the CIGSSe films were changed by annealing temperature and film thickness. The band gap energy were found approximately 1.5 eV with the different film thickness. [ABSTRACT FROM AUTHOR]

Al-doped SnS thin films with different Al concentrations were deposited on fluorine doped tin oxide (FTO) substrate from aqueous solution containing 2 mM SnCl2 and 20 mM Na2S2O3 and various amounts of 5 mM AlCl3 solution. The pH, temperature, time, and deposition potential ( E) of the solution were kept at 2.1, 60 °C, 30 min and −1 V, respectively. The deposited films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL), and UV-Vis. XRD patterns obviously indicated that the synthesized Al-doped SnS were polycrystalline with orthorhombic structure and by increasing the amount of Al concentration, the crystallinity was increased. The FESEM images showed that the morphology of the nanostructures was changed with increasing Al content. PL and UV-Vis analysis were used to investigate the optical properties of materials. The PL spectra showed a red shift with increasing of Al concentration. [ABSTRACT FROM AUTHOR]

Cu 2 SnSe 3 (CTSe) is a polyvalent material that can be used as an absorber layer for thin film solar cells or as a starting layer for the synthesis of CZTSe or CZTSSe compounds. Obtaining CTSe single phase films with optimized properties for thin film solar cells is a difficult task. A systematic study using both metallic and binary chalcogenides precursors for the formation of the CTSe phase was not performed. The films consisting of four different stacks (Sn\Cu, SnSe 2 \Cu, Sn\Cu 2 Se, and SnSe 2 \Cu 2 Se) were prepared by magnetron sputtering on soda lime glass (SLG) and molybdenum (Mo) coated SLG substrates, followed by annealing at 550 °C under Sn + Se atmosphere. X-ray diffraction and Raman spectroscopy results indicated the formation of a single CTSe phase in most of the stacks deposited on both substrates. Scanning electron microscopy images showed compact surfaces with large grains in the films deposited on Mo substrate, while the films on SLG have more voids on their surfaces. The elemental analysis measured by energy dispersive spectroscopy revealed stoichiometric films on Mo, and copper and tin rich compositions on SLG substrates. The band gap values inferred by conventional spectroscopy are between 0.81 and 1.95 eV. It was found that the SnSe 2 \Cu and Sn\Cu 2 Se stacks are preferred for the formation of a single CTSe phase, with dense surface morphology, a stoichiometric composition, and an optimal absorber layer band gap. This study opens the way to comprehend the formation reactions during the selenization of metallic and binary chalcogenides precursors towards the optimization of kesterite absorber for photovoltaic device fabrication. • Different stacks were prepared by MS using Cu, Cu 2 Se, Sn and SnSe 2 targets. • Stacks were deposited on SLG and Mo substrates and annealed at 550 °C. • Two metals or a metal and a binary chalcogenide lead to single phase CTSe films. • The SnSe 2 \Cu or Sn\Cu 2 Se stacks have the best properties for absorber layers. [ABSTRACT FROM AUTHOR]

The use of a wide bandgap absorber layer in the top cell of a multi-junction silicon thin film solar cell is necessary to achieve a high-conversion efficiency. A higher bandgap of the absorber results in a higher open-circuit voltage ( Voc) of the cell. In this work, intrinsic hydrogenated amorphous silicon oxide (i)a-SiO:H films have been prepared by using 13.56 MHz radio frequency plasma enhanced chemical vapour deposition (RF-PECVD) at a substrate temperature of 195 °C. The carbon dioxide (CO2) to silane (SiH4) ratio rc was varied and the influence of the ratio rc on the optoelectronic film properties was investigated. These thin films have been studied in detail in terms of their dark ( σd) and photo ( σph) conductivity and photoresponse PR ( σph/ σd). The defect density Nd and Urbach energy EU were determined by constant photocurrent method (CPM). The optical bandgap Eg,Tauc was derived from Tauc plots. Optical constants were determined by spectroscopic ellipsometry measurements in the range between 300 and 1000 nm. It was found that the increase in the CO2 to SiH4 ratio rc not only leads to a higher optical bandgap, but also higher defect density Nd and Urbach energy EU and on the other hand to a lower photoresponse PR. A suitable photoresponse PR = 8.64 × 105 at a high bandgap of Eg,Tauc = 1.91 eV and a defect density of Nd = 1.7 × 1016 cm−3 was achieved. The refraction index and extinction coefficient were lowered with increasing rc. The analysis of light-induced degradation in the (i)a-SiO:H layers showed a smaller increase of deep defects Nd and a higher increase of the Urbach energy EU in terms of the light soaking time with respect to the (i)a-Si:H reference layer. [ABSTRACT FROM AUTHOR]

Thin polycrystalline CuInSe2 (CIS) films for photovoltaic (PV) applications were deposited on molybdenum (Mo)-coated soda lime glass substrates by the one-step electrodeposition process. Films growth was carried out using low concentration aqueous sulfate-based single baths containing dilute CuSO4.5H2O, In2(SO4)3.H2O and SeO2. The electrodeposited CIS layers were studied using SEM, EDS, X-ray diffraction and optical analyses. It was found that film microstructure, composition and morphology strongly depend on the initial concentrations of Cu(II), In(III) and Se(IV) electro-active ionic species in the electrochemical bath. Investigations on the films structure have shown that as-deposited samples are composed of microcrystalline and/or amorphous materials and require recrystallization at high temperature for device processing. Annealing in H2Se atmosphere at 450 °C led to highly crystallized thin films exhibiting the chalcopyrite structure with a pronounced (112) orientation. Optimized processing conditions for high quality thin CIS absorber materials have been established and subsequent photovoltaic (PV) devices exhibited ~ 9% efficiency.

Abstract: Thin films of SnS (tin sulphide) were thermally evaporated onto glass and CdS/ITO (cadmium sulphide/indium tin oxide) coated glass substrates and then annealed in vacuum with the aim of optimising them for use in photovoltaic solar cell device structures. The chemical and physical properties of the layers were determined using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction, and transmittance versus wavelength measurements. “Superstrate configuration” devices were also made using indium tin oxide as the transparent conductive oxide, thermally evaporated cadmium sulphide as the buffer layer and evaporated copper/indium as the back contact material. Capacitance–voltage data are given for the fabricated devices. Capacitance–voltage, spectral response and I–V data are given for the fabricated devices. [Copyright &y& Elsevier]

Abstract: SnS (tin sulphide) is of interest for use as an absorber layer and the wider energy bandgap phases e.g. SnS2, Sn2S3 and Sn/S/O alloys of interest as Cd-free buffer layers for use in thin film solar cells. In this work thin films of tin sulphide have been thermally evaporated onto glass and SnO2:coated glass substrates with the aim of optimising the properties of the material for use in photovoltaic solar cell device structures. In particular the effects of source temperature, substrate temperature, deposition rate and film thickness on the chemical and physical properties of the layers were investigated. Energy dispersive X-ray analysis was used to determine the film composition, X-ray diffraction to determine the phases present and structure of each phase, transmittance and reflectance versus wavelength measurements to determine the energy bandgap and scanning electron microscopy to observe the surface topology and topography and the properties correlated to the deposition parameters. Using the optimised conditions it is possible to produce thin films of tin sulphide that are pinhole free, conformal to the substrate and that consist of densely packed columnar grains. The composition, phases present and the optical properties of the layers deposited were found to be highly sensitive to the deposition conditions. Energy bandgaps in the range 1.55 eV–1.7 eV were obtained for a film thickness of 0.8 μm, and increasing the film thickness to >1 μm resulted in a reduction of the energy bandgap to less than 1.55 eV. The applicability of using these films in photovoltaic solar cell device structures is also discussed. [Copyright &y& Elsevier]

Abstract: SnS is of interest for use as an absorber layer and the wider energy bandgap phases e.g. SnS2, Sn2S3 and Sn/S/O alloys of interest as Cd-free buffer layers for use in thin film solar cells. In this work thin films of tin sulphide have been thermally evaporated onto soda–lime glass substrates with the aim of optimising the properties of the material for use in superstrate configuration device structures. The thin films were characterised using energy dispersive X-ray analysis (EDS) to determine the film composition, X-ray diffraction (XRD) to determine the phases present and structure of each phase, transmittance versus wavelength measurements to determine the energy bandgap and scanning electron microscopy (SEM) to observe the surface topology and topography. These properties were then correlated to the deposition parameters. Using the optimised conditions it is possible to produce thin films of tin sulphide that are pinhole free and conformal to the substrate that are suitable for use in thin film solar cell structures. [Copyright &y& Elsevier]

Abstract: CuInSe2 (CIS) thin films were deposited on Mo/glass substrates by one-step electrodeposition from aqueous baths containing CuSO4, In2(SO4)3 and SeO2 with Li2SO4 electrolyte. The quality of the electrodeposited films depended on the presence of pH buffer in the bath. CIS films deposited from non-pH buffered baths showed pronounced (112) orientation, while films exhibiting more random orientation were obtained from pH buffered baths. Denser, smoother samples were obtained from non-pH buffered baths, though with no difference in film composition. As-deposited films exhibit low crystallinity and require recrystallization by annealing in H2Se. Best devices, ∼9%, were obtained with CuInSe2 films deposited from non-pH buffered baths. [Copyright &y& Elsevier]

We present a first-principles computational study of cation–Se Σ 3 (112) grain boundaries in CuGaSe 2. We discuss the structure of these grain boundaries, as well as the effect of native defects and Na impurities on their electronic properties. The formation energies show that the defects will tend to form preferentially at the grain boundaries, rather than in the grain interiors. We find that in Ga-rich growth conditions Cu vacancies as well as Ga at Cu and Cu at Ga antisites are mainly responsible for having the equilibrium Fermi level pinned toward the middle of the gap, resulting in carrier depletion. The Na at Cu impurity in its +1 charge state contributes to this. In Ga-poor growth conditions, on the other hand, the formation energies of Cu vacancies and Ga at Cu antisites are comparatively too high for any significant influence on carrier density or on the equilibrium Fermi level position. Thus, under these conditions, the Cu at Ga antisites give rise to a p -type grain boundary. Also, their formation energy is lower than the formation energy of Na at Cu impurities. Thus, the latter will fail to act as a hole barrier preventing recombination at the grain boundary, in contrast to what occurs in CuInSe 2 grain boundaries. We also discuss the effect of the defects on the electronic properties of bulk CuGaSe 2 , which we assume reflect the properties of the grain interiors. [ABSTRACT FROM AUTHOR]

Copper–indium–gallium–selenide (CIGSe) is one of the most stable and promising materials for photovoltaic applications. Herein, the synthesis process of CIGSe nanocrystals using a tri‐octyl phosphine/tri‐octyl phosphine oxide (TOP/TOPO) method that has the shortest duration (≈45 min), as compared to other nonvacuum‐based approaches, is reported. Most solution‐based approaches are Se‐deficient and therefore utilize a post‐selenization process such as rapid thermal processing (RTP) at a high temperature to form CIGSe. RTP creates voids and defects in CIGSe films. The synthesis process does not need post‐selenization processes as it is not Se‐deficient. It also includes the purification and processing techniques of these CIGSe nanocrystals for a variety of printing and coating techniques. The purification process offers improved charge transport between CIGSe nanocrystals for the realization of efficient photovoltaic device without resorting to soda lime glass (SLG), post‐deposition thermal selenization, or harsh chemical treatments. In addition, this process avoids the incidence of contamination, such as with copper selenide and amorphous carbon, which is a common issue in solution‐based techniques, and thus provides high‐purity CIGSe ink. To identify the effects of the purification process, the synthesized ink is qualitatively and quantitatively characterized before and after each purification step. [ABSTRACT FROM AUTHOR]