Highly efficient lead-free silver bismuth iodide (Ag3BiI6) rudorffite solar cells with novel device architecture: A numerical study

Solar cells (SCs) based on non-toxic, lead-free silver bismuth iodide (SBI, Ag3BiI6) absorbers have recently gained tremendous attention compared to lead halide perovskites. However, the actual device efficiency still does not exceed 6%. Therefore, finding a suitable SBI SC architecture with proper ETL and HTL layers is crucial to attaining maximum performance. In this research, the SCAPS-1D simulation is used to design the SC, consisting of an SBI-absorber, CeOx-ETL, and three different HTLs (pristine Cu2O, Te & Se/Te doped Cu2O) under the standard illumination. After optimization of all layers thickness and defect densities, the Se/Te-Cu2O-HTL device showed a maximum efficiency of 17.7% with a higher built-in potential (1.37 V) than other HTL devices (16.5%, 1.31 V for Te-Cu2O & 16%, 1.25 V for Cu2O) due to its enhanced hole transfer and reduced recombination at the Ag3BiI6/HTL interface. Besides, the impact of radiative recombinations, parasitic resistances, capacitance, MottSchottky, Nyquist plot and working temperature are carefully examined. The Voc deficit increases by increasing the operating temperature, and visibly, Se/Te-Cu2O (0.49 V) shows a higher Voc deficit than Te-Cu2O (0.39 V) and Cu2O (0.34 V) HTL devices. Overall, our findings can be helpful to experimentalists to reach high efficiency in the near future.