Performance evaluation of WS₂ as buffer and Sb₂S₃ as hole transport layer in CZTS solar cell by numerical simulation

Abstract

This study reports on performance enhancement of a Cu2ZnSnS4 solar cell introducing Sb2S3 as hole transport layer (HTL) along WS2 as buffer layer. We have investigated photovoltaic (PV) characteristics by utilizing SCAPS‐1D. A comparative analysis on PV performances between conventional CZTS/CdS and proposed Ni/Sb2S3/CZTS/WS2/FTO/Al solar cells is presented. It is revealed that “spike like” band structure at the CZTS/WS2 interface having smaller conduction band offset makes it potential alternative to commonly used CdS buffer. This report also evaluates that the Sb2S3 as an HTL inserted at the rear of CZTS enhances performances by reducing carrier recombination at back interface with appropriate band alignment. The impacts of thickness, carrier concentration of different layers, and bulk defect density in CZTS as well as the interface defects on cell outputs are analyzed. The influences of temperature, work function, and cell resistances are also examined. Optimum absorber thickness of 1.0 μm along doping density of 1017 cm−3 is selected. A maximum efficiency of 30.63% is achieved for the optimized CZTS cell. Therefore, these results suggest that Sb2S3 as HTL and WS2 as buffer layer can be employed effectively to develop highly efficient and low‐cost CZTS solar cells.

Investigation on the Performance Enhancement of Heterojunction SnS Thin-Film Solar Cell with a Zn3P2 Hole Transport Layer and a TiO2 Electron Transport Layer

“…45,74,78−80 Thus, the performance enhancements are due to the diminution in minority carrier (electron) recombination loss at the back surface of the heterojunction TFSC. [43][44][45][46][47]70,75,81 The PCE of the SnS cell with Zn 3 P 2 HTL is found to be 30.45%, which is superior as compared to the efficiencies of 25.59% for CuI, 27.87% for CuS, and 25.43% for Cu 2 O HTLs, respectively. The energy band diagrams for the SnS PV devices with several HTLs are illustrated in Figure 3b.…”

“…Table 1 presents the simulation parameters employed for various layers in the heterojunction SnS-based PV devices. 17,39,40,47,51 Numerous materials with electron and hole thermal velocities of 10 7 cm s −1 have been used. 45−47 Also, the following equation can be used to determine the absorption coefficient (α) 74 A h E ( )…”

“…40,47−50 These PV improvements may be due to the decline of nonradiative carrier recombination at the front contact by ensuring accurate band orientation with the active layer. 40,47,50 In previous studies, the device outputs of various thin-film PV energy systems have been enlarged by applying numerous inorganic HTLs, such as CuI, CuS, Cu 2 O, and Zn 3 P 2 , at the back of the absorber in the heterostructure. 42−44,46,51−53 It has also been conferred that several Cd-free ETLs, such as ZnSe, SnO 2 , ZnO, ZnS, ZnMgO, In 2 S 3 , TiO 2 , WS 2 etc., can be helpful to boost the device efficiency.…”

“…51,67−69 Additionally, a low valence band offset (VBO) at the Zn 3 P 2 HTL/SnS absorber contact is predicted which will ensure easy hole passage from the absorber to the rear contact. 40,47 It is also expected that the addition of earth-abundant Zn 3 P 2 semiconductor as an HTL with promising optoelectronic properties will minimize the total expenditure of the solar system by lessening the absorber thickness. 70 In this study, the 1D solar cell capacitance simulator (SCAPS-1D) software program is applied to scheme and evaluate the functions of a new SnS-based TFSC.…”

“…Simulation Parameters Employed for Various Layers in Heterojunction SnS-Based PV Devices17,39,40,47,51 …”