Compositional engineering and surface passivation for carbon-based perovskite solar cells with superior thermal and moisture stability

The inherent stability of perovskite absorbers towards environmental factors is a major limitation towards commercializing perovskite solar cells (PSCs). In this regard, MaPbI3 (MAPI) is engineered to attain thermal stability by incorporating Guanidinium iodide (GuI) and moisture stability by surface passivation using 5- amino valeric acid iodide (5-AVAI). The surface passivation of Gu modified MAPI, hereafter termed as GUMAPI, exhibits a 2D/3D perovskite interface, which, facilitates perovskite to attain high moisture and temperature stability. Various concentrations of 5-AVAI are used as the surface passivator. The stability of the surface-modified Gu doped MAPI films is studied thoroughly using time-dependent water contact angle measurements, in-situ temperature-dependent XRD analysis, and XRD studies of aged perovskite films under ambient conditions. 1AV films exhibit excellent temperature (>150 °C) and ambient stability (>59 days) when compared with control perovskite films (GUMAPI). The stability and performance of these perovskite films in a carbon-PSCs (CPSCs) architecture are evaluated by studying the current-voltage characteristics and assessing the device performance at various intervals. The 1AV-based CPSCs exhibit performance surpassing the control (GUMAPI) devices. A 9.0% increment is observed in the 1AV-based CPSCs compared to the GUMAPI-based CPSCs with an efficiency of 13.2% and a T80 lifetime of 93.2% without encapsulation.