Impact of stress testing and passivation strategies on low-cost carbon-based perovskite solar cell under ambient conditions

Abstract The use of organolead trihalide perovskite material has been an important milestone in the field of photovoltaics with power conversion efficiencies reaching up to 25.6% in 2021. The light absorbing layer of the perovskite solar cell (PSC) plays a pivotal role in establishing long-term efficiency and stability. Stabilization of these perovskite phases is crucial for the efficient charge transfer dynamics, leading to a better optoelectronic performance. However, the perovskite layer may undergo undesirable phase transitions when exposed to environmental stressors. This impediment can be allayed by having a better understanding of the stress testing regimes and proper passivation strategies leading to their commercial scalability. In the present study, three types of perovskite materials are used for stress testing so as to observe the influence of atmospheric stressors on the type of perovskite materials used. An accelerated ageing test was performed on PSCs with simultaneous combination of heat and humidity. Our results show that FA-MA-Cs based mixed cationic lead halide perovskite are better suited for endurance against environmental stressors retaining almost 50% of PCE post stress test. The champion PSC samples were then subjected to two different modes of low-cost passivation techniques for perovskite absorber layer using acetic acid and CaCl2 as passivating agents. Acetic acid treated samples managed to have lower hysteresis values, lower yellow phase-based degradation and a PCE of up to 15% as compared to control samples. CaCl2 treated samples on the other hand had improved open-circuit voltage values and had more homogenous distribution with better resistance against recombined electrons.