The impact of SnMnO2 TCO and Cu2O as a hole transport layer on CIGSSe solar cell performance improvement

Abstract

In this work, two experimental CIGSSe thin-film solar cells (TFSCs) are simulated and demonstrate high efficiency of 20 and 22.92%. The photovoltaic results of both devices are then validated based on the experiential optoelectronic values. After the simulation, a compelling result is confirmed for both the experimental and simulated solar cells. Finally, various designs are proposed. The proposed Type-1 solar cell is designed by the addition of low resistivity, wide energy bandgap (E_g), and minimum absorption coefficient (α) based tin-doped manganese oxide (Sn_1−xMn_xO₂) material in a conventional solar cell instead of ZnO:B and ZnMgO:Al transparent conducting oxide (TCO) layers. Further, by matching the band energy alignment and adjusting the thickness and doping concentration of the TCO, buffer, and absorber layers, the efficiency of the proposed Type1 TFSC has been increased from 20 to 27.75%. The proposed Type-1 solar cell has some drawbacks, such as the inability to appropriately suppress the photogenerated minority carrier recombination losses due to the absence of a hole transport layer (HTL), and the external quantum efficiency (EQE) is lower than that of the conventional solar cell. Furthermore, wide band energy and a high α based on cuprous oxide (Cu₂O) as an HTL are added between the absorber and the back ohmic contact layers in the proposed Type-1 solar cell. Then the structure becomes a Type-2 TFSC. The Type-2 TFSC absorbs more blue light, instantly suppressing the recombination losses and enhancing power conversion efficiency (PCE) (η = 29.01%) and EQE (97%).