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Quantum bandgap buffer layers can improve sunlight absorption in the short wavelength region, hence improving the performance of CIGS solar cells. In this study, we use numerical modelling to determine the impact of various buffer layers' electrical characteristics on the performance of CIGS thin film photovoltaic devices, particularly, carrier concentration and the quantum effect. As well Ag 2 S buffer layer has been experimentally examined to fulfilment its effect in term of bulk and quantum bandgap. Experimental results depicted that, Ag 2 S QDs has polycrystalline nature of films, with smooth surface roughness, and average diameter 4 nm. Meanwhile, a simulation revealed that the Fermi level of the ( n -buffer layer) material shifts closer to the conduction band with an increase in carrier concentration. The findings indicate that, a buffer layer with a wider bandgap and carrier concentration is an essential demand for achieving a device with a higher conversion efficiency and a broader bandgap-CBO window. It was attributed to beneficial synergistic effects of high carrier concentration and narrower depletion region, which enable carriers to overcome high CBO barrier. Most importantly, modelling results indicate that the optic-electrical characteristics of the buffer layer are critical in determining the progress of a CIGS solar cell.

In this study, we aimed to increase the knowledge regarding the response mechanisms which were associated with the formation of CdS thin films. CdS thin film remains the most appealing alternative for many researchers, as it has been a capable buffer material for effect in film based polycrystalline solar cells (CdTe, CIGSe, CZTS). The Linker Assisted and Chemical Bath Deposition (LA-CBD) technique, which combines the Linker Assisted (LA) technique and the chemical bath deposition (CBD) method for forming high quality CdS thin film, was presented as an efficient and novel hybrid sensitization technique. CdS films were bound to soda lime with the help of electrostatic forces, which led to the formation of the intermediate complexes [Cd (NH 3 ) 4 ] 2+ that helped in the collision of these complexes with a soda lime slide. Salvia dye and as a linker molecule 3-Mercaptopropionic acid (MPA) was used in the one step fabrication technique. Optical results showed that the bandgap varied in the range of (2.50 to 2.17) eV. Morphological properties showed a homogeneous distribution of the particles that aspherical in shape in the CdS + MPA + Salvia dye films. This technique significantly affected on the electrical characterizations of CdS films after the annealing process. The CdS + Ag + MPA + Salvia dye films showed the maximum carrier concentration and minimum resistivity, as 5.64 × 10 18  cm −3 and 0.83 Ω cm respectively.

This study aims to enhance the CZTS device's overall efficiency, the key research area has been identified in this study is to explore the effects of a novel, low-cost, and simplified, deposition method to improve the optoelectronic properties of the buffer layer in the fabrication of CZTS thin film solar cells. Herein, an effective way of addressing this challenge is through adjusting the absorbers' structure by the concept of doping, sensitized CdS thin film by the bi-functional linker, and an environmentally friendly catalytic green agent. The Linker Assisted and Chemical Bath Deposition (LA-CBD) method was introduced as an innovative and effective hybrid sensitization approach. In the one-step synthesis process, Salvia dye, Ag, and 3-Mercaptopropionic acid (MPA) were used. Generally, the results for all samples displayed varying bandgap as achieved between (2.21–2.46) eV, hexagonal structure with considerably decreased strain level, broader grain size, and dramatically enhanced crystalline property. Hence, the rudimentary CdS/CZTS solar cell devices were fabricated for the application of these novel CdS films. Preliminary CZTS thin film solar cell fabrication results in the highest conversion efficiency of 0.266% obtained CdS + Salvia dye, indicating the potential use of the CdS films as a buffer layer for CZTS photovoltaic devices.

Surface alteration of titanium dioxide nanotube arrays by semiconductor and metal is one of the pathways to narrow the wide bandgap of titanium dioxide and thereby increase its absorption in the visible region. Cu-CdSe-cosensitized titanium dioxide nanotube arrays (Cu-CdSe/TiO 2 nanotube) have been produced for use as photoanodes in photoelectrochemical cells. Ordered Cu-CdSe/TiO 2 nanotubes were successfully prepared by varying the deposition time (1 min to 4 min) using a facile three-step electrochemical method. The composition, morphological structure, and visible-light response were characterized by field-emission scanning electron microscopy, x-ray diffraction (XRD) analysis, energy-dispersive x-ray spectroscopy, ultraviolet–visible (UV–Vis) diffusion reflection spectroscopy (DRS), and photoelectrochemical testing. XRD analysis demonstrated that sensitization using Cu-CdSe did not destroy the structure of the anatase-phase nanotube arrays, with the formation of copper nanoparticles composed of cubic-like particles with increasing deposition time. UV–Vis DRS of the Cu-CdSe/TiO 2 nanotubes revealed a red-shift of the photoresponse towards the visible-light region, characterized by bandgap narrowing and improved photoefficiency. The optimal photoelectrochemical performance was observed when depositing Cu nanoparticles for 1 min, surpassing that of pristine titania nanotube arrays and other materials prepared under different conditions. The features of these photoanodes for many applications include easy synthesis, low cost, high efficiency for visible lighting, and good stability. The present work demonstrates a feasible modification of TiO 2 nanotubes with Cu-CdSe to form potential photoanodes for solar conversion devices.

In this study, Cu 2 S/ZnO nanorods arrays (NRAs) nanocomposite have been efficiently papered via dual methods: firstly, ZnO NRAs by a hydrothermal method, and secondly Cu 2 S nanoparticles via successive ionic layer adsorption (SILAR). Cu 2 S/ZnO photoelectrode is collected from ZnO which is presented as a fast electron transportation way because of its high mobility and Cu 2 S as good sensitized material due to its small energy gap. XRD analysis, FESEM images, EDX analysis, UV–Vis spectra and photoelectrochemical performance (PEC) of bra ZnO and Cu 2 S/ZnO were characterized. All characterizations have confirmed formed the Cu 2 S/ZnO NRAs nanocomposite. PEC measurement was strong evidence to synthesis of Cu 2 S/ZnO which exhibited the anodic photocurrent density of pure ZnO NRs (0.12 mA cm −2 ) that was lower than Cu 2 S/ZnO NRAs (0.93 mA cm −2 ) at 1.0 V vs. Ag/AgCl.

Despite its large band gap, ZnO has wide applicability in many fields ranging from gas sensors to solar cells. ZnO was chosen over other materials because of its large exciton binding energy (60 meV) and its stability to high-energy radiation. In this study, ZnO nanorods were deposited on ITO glass via a simple dip coating followed by a hydrothermal growth. The morphological, structural and compositional characteristics of the prepared films were analyzed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Photoelectrochemical conversion efficiencies were evaluated via photocurrent measurements under calibrated halogen lamp illumination. Thin film prepared at 120 °C for 4 h of hydrothermal treatment possessed a hexagonal wurtzite structure with the crystallite size of 19.2 nm. The average diameter of the ZnO nanorods was 37.7 nm and the thickness was found to be 2680.2 nm. According to FESEM images, as the hydrothermal growth temperature increases, the nanorod diameter become smaller. Moreover, the thickness of the nanorods increase with the growth time. Therefore, the sample prepared at 120 °C for 4 h displayed an impressive photoresponse by achieving high current density of 0.1944 mA/cm2.

This research focuses on improving the photoelectrochemical performance of binary heterostructure Ag2S/ZnO NRs/ITO by manipulating synthesis conditions, particularly the concentrations of sliver nitrate AgNO3 and thiourea CS(NH2)2. The photoelectrochemical performance of Ag2S/ZnO nanorods on indium tin oxide (ITO) nanocomposite was compared to pristine ZnO NRs/ITO photoanode. The hydrothermal technique, an eco-friendly, low-cost method, was used to successfully produce Ag2S/ZnO NRs at different concentrations of AgNO3 and CS(NH2)2. The obtained thin films were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), and photoelectrochemical studies (PECs). We observed that there was an enhancement in absorbance in the visible region and effective photoelectron transfer between the Ag2S/ZnO NRs/ITO photoelectrode and the electrolyte Red-Ox when illuminated with 100 mW cm−2. Increasing the concentration of AgNO3 caused a remarkable decrease in the optical bandgap energy (Eg) values. However, we noticed that there was an unstable trend in Eg when the concentration of CS(NH2)2 was adjusted. The photoelectrochemical studies revealed that at a bias of 1.0 V, and 0.005 M of AgNO3 and 0.03 M of CS(NH2)2, the maximum photocurrent of the Ag2S/ZnO NRs/ITO photoanode was 3.97 mA/cm2, which is almost 11 times that of plain ZnO nanorods. Based on the outcomes of this investigating, the Ag2S/ZnO NRs/ITO photoanode is proposed as a viable alternative photoanode in photoelectrochemical applications.

ZnO-nanoflowers on a transparent conductive tin-doped In2O3 (ITO) glass substrate have been successfully prepared via a simple and efficient growth approach that is combining of dip coating and hydrothermal processes. One thin layer of ZnO nanoparticles is prepared by dip coating method followed by hydrothermally grown of ZnO nanoflowers at low temperature. The morphology and structure of ZnO-nanoflowers were inspected by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD), respectively. The optical absorption and photoluminescence spectra of ZnO-nanoflowers are also investigated. The ZnO-nanoflowers photoanode shows dramatically contributed to the separation of electron-hole pairs and enhanced the photoresponse. The photocurrent density is 0.44 mA/cm2 indicated that the PEC cells based on ZnO-nanoflowers photoanode have promising application potential in overall solar energy.

ZnO nanoparticles/ZnO nanorods (ZnO NPs/ZnO NRs) were prepared via Chemical methods: dip-coating/sol-gel method (DC/SG-M) and hydrothermal method (HT-M). The structure of ZnO NPs/ZnO NRs was studied utilizing X-ray diffraction (XRD). The UV-Visible spectrometer was used to analyze the absorption spectra. Surface morphology of prepared ZnO NPs/ZnO NRs was studied via field-emission scanning electron microscopy (FE-SEM). Starting with (XRD) study, it confirms that the prepared ZnO NPs/ZnO NRs has the hexagonal phase structure. Moreover, the average crystallite size of the ZnO NPs/ZnO NRs was 22.7 nm and 51.5 nm, respectively. FE-SEM result reveals that the prepared ZnO NPs/ZnO NRs samples have shown the nanoparticles-shape of the first prepared layer via dip-coating and radial hexagonal-shape of the second prepared layer via the hydrothermal method. The absorption spectra of ZnO NPs and ZnO NRs were around at (382 and 400) nm with the estimated direct band gaps energy were (3.24 and 3.10) eV, respectively.

Antimony trisulfide (Sb2Se3), a non-toxic and accessible substance, has possibilities as a material for use in solar cells. The current study numerically analyses Sb2Se3 solar cells through the program Solar Cell Capacitance Simulator (SCAPS). A detailed simulation and analysis of the influence of the Sb2Se3 layer’s thickness, defect density, band gap, energy level, and carrier concentration on the devices’ performance are carried out. The results indicate that a good device performance is guaranteed with the following values in the Sb2Se3 layer: an 800 optimal thickness for the Sb2Se3 absorber; less than 1015 cm−3 for the absorber defect density; a 1.2 eV optimum band gap; a 0.1 eV energy level (above the valence band); and a 1014 cm−3 carrier concentration. The highest efficiency of 30% can be attained following optimization of diverse parameters. The simulation outcomes offer beneficial insights and directions for designing and engineering Sb2Se3 solar cells.