Molybdenum doped tin oxide as electron transport material in air-processable perovskite solar cells

The presence of carrier traps, originating from oxygen vacancies in the electron transport layer (ETL), significantly impacts both the efficiency and power hysteresis of perovskite solar cells. This study successfully demonstrated that the incorporation of molybdenum (Mo) dopants into the SnO₂ ETL effectively mitigates carrier traps, leading to an enhancement in the power conversion efficiency of perovskite solar cells prepared under ambient conditions. The process of Mo doping in SnO₂ involves a straightforward application of molybdenum salt onto the SnO₂ layer via spin coating, followed by annealing at 185 °C for 1 h. Raman analysis reveals that the presence of Mo in the SnO₂ lattice resulted in subtle modifications to the in-plane Sn–O stretching mode vibration (Eg), modifying the optoelectrical properties of SnO₂. The champion Mo–SnO₂ ETL based perovskite solar cells exhibits an impressive power conversion efficiency as high as 7.33% with V_oc, J_sc and FF as high as 0.88 V, 16.02 mA/cm⁻², and 0.52, respectively. It is significantly higher than the pristine SnO₂ ETL based device. These figures represent a significant advancement over devices employing pristine SnO₂ ETLs. An analysis of power hysteresis indicated that the utilization of Mo-doped SnO₂ ETLs effectively reduced hysteresis effects in the devices, suggesting efficient defect passivation within the device structure. These findings highlight the promising potential of Mo-doped SnO₂ ETLs for applications in perovskite solar cells with low power hysteresis.