Here, we report an enhanced photovoltaic (PV) performance including open circuit voltage (V_oc), short circuit current (J_sc), fill factor (FF) and power conversion efficiency (PCE) of Ni/PEDOT:PSS/n-Si/n-ZnO/Al heterojunction solar cells (HSCs) via numerical simulation. In this structure, n-ZnO is introduced at the interface of Si and Al as back surface field (BSF). Firstly, influence of various device parameters, such as thickness of Si, and PEDOT:PSS layers, carrier concentrations and defect density of Si and PEDOT:PSS on the PV performances of device without ZnO-BSF has been investigated numerically employing Solar Cell Capacitance Simulator (SCAPS-1D) software to find the best possible performance parameters of such HSCs. The maximum PCE of the optimized PEDOT:PSS/n-Si HSC without BSF is achieved as 24.26% with V_oc: 0.647 V, J_sc: 44.87 mA/cm², and FF: 83.52% for t_Si of 150 μm with N_d of 1 × 10¹⁶ cm⁻³. After introducing the ZnO-BSF layer of thickness and carrier concentration of 20 nm and 1 × 10¹⁷ cm⁻³ respectively, the significant enhancement in the PCE of the device has been observed. The PCE as high as 31.37% with V_oc: 0.784 V, J_sc: 45.31 mA/cm², and FF: 88.35% was obtained for an optimized ZnO-BSF layer. The PCE is more than 7% (absolute) higher than that of without ZnO-BSF layer. The significant improvement in the PV parameters, primarily in V_oc by ~ 137 mV was caused by high built-in potential developed across the junction after insertion of the ZnO-BSF layer. The quantum efficiency of the device further supported the enhanced performance resulting from the reduced recombination of charge carriers at the rear side after n-ZnO-BSF layer. The present numerical simulation study proposes a great potential of ZnO as the BSF layer for the enhanced PV performance of PEDOT:PSS/n-Si based HSCs.

Graphical abstract