Effect of sputtering power on the performance of p-Ni_1−xO:Li/n-Si heterojunction solar cells

This study investigates the effects of sputtering power on the performance of p-Ni_1−xO:Li/n-Si heterojunction solar cells (HJSCs). The results of this study indicate a strong dependence of the cell characteristics on the sputtering power. Extremely high or low sputtering power generates higher interface state density (D_it), resulting in the lowering of open circuit voltage (V_oc) and fill factor (FF). The cell fabricated at a sputtering power of 100 W has the lowest D_it of 7.08 × 10¹¹ cm⁻² eV⁻¹, corresponding to the highest conversion efficiency (η) of 4.30 % [short circuit current density (J_sc): 18.06 mA cm⁻², V_oc: 390 mV, FF: 61.1 %, series resistance (R_s): 4.3 Ωcm² and shunt resistance (R_sh): 478.75 Ωcm²]. Furthermore, the cell exhibits a considerably poor temperature coefficient of −0.70 %/ °C (J_sc: +0.07 %/°C, V_oc: −0.52 %/°C and FF: −0.29 %/°C) when compared with conventional solar cells. Further improvement in the D_it of the cell is highly imperative for developing p-Ni_1−xO:Li/n-Si HJSCs with a high conversion efficiency and a good temperature coefficient.