SCAPS study on the effect of various hole transport layer on highly efficient 31.86% eco-friendly CZTS based solar...

Copper Zinc Tin Sulphide (CZTS) is a propitious semiconductor for active absorber material in thin-film solar cells (SCs). Here, SC architecture comprising FTO/ZnS/CZTS/variable HTLs/Au is discussed. Fluorine-doped tin oxide (FTO) and gold (Au) are used as front and back contacts, respectively. Zinc sulphide (ZnS) is used as an active electron transport layer (ETL), while different Cu-based materials (Cu₂O, CuO, CuI, and CuSCN) are used as hole transport layers (HTL). A one-dimensional solar cell capacitance simulator (SCAPS-1D) is utilized to simulate the SC structure. Among different Cu-based HTLs, Cu₂O is preferred as a potential candidate for high cell performance of CZTS-based SC. The effects of various layer parameters such as thickness, doping density, and carrier concentrations, electron affinity of HTL and absorber, respectively, are also discussed. After optimization of the device, variation of operating temperature and the effect of series and shunt resistance are also taken into consideration. The optimized results of thickness and acceptor concentration (N_A) of absorber material are 1.5 µm and approx. 1.0 × 10¹⁹ cm^-3, respectively. In addition, the function of HTL (with and without) in the designed SC structure is also studied. Capacitance-voltage (C-V) characteristics are also discussed to get an insight of built-in potential. We have achieved cell performances viz. efficiency = 31.86%, short circuit current density = 32.05 mA/cm², open circuit voltage = 1.19 V, and fill factor = 83.37%.