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, Mott-Schottky, 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.