Fluoroarene derivative based passivation of perovskite solar cells exhibiting excellent ambient and thermo-stability achieving efficiency >20

Hybrid perovskite solar cells (PVSCs) are extremely susceptible to moisture and heat, which restricts their commercial viability. Herein, three multifunctional fluoroaromatic amine additives i.e. 4-fluoroaniline (FA), 2,4,6-trifluoroaniline (TFA) and 2,3,4,5,6-pentafluoroaniline (PFA) are utilized as passivating additives to enhance the stability of the perovskite films, thereby improving the efficiency of PVSCs. Among these fluorinated aromatic amines, PFA most proficiently improved the efficiency along with the moisture and thermo-stability of MAPbI 3 based PVSCs. PFA significantly passivated the defects and assisted better charge transport in the devices. The power conversion efficiency (PCE) was enhanced beyond 20% for the PFA passivated device, compared to the 15.08% of the pristine device without any passivation. Moreover, the PFA passivated device retained up to 87% PCE, compared to 26% for the pristine device when exposed to relative humidity ∼50% for 1000 h. The fluorine atoms attached to the passivation additives were able to provide protection to the PVSCs against moisture induced erosion. Moreover, only 10% efficiency was maintained by the pristine device in comparison to 82% for the PFA based device after 20 h of heating at 100 °C inside a glovebox. Thus this work presented a generic approach to improve the overall stability and performances of PVSCs, thereby widening the possibility towards practical applications. Trap states in perovskite thin films were passivated effectively by pentafluoroaniline (PFA) additive, thereby significantly enhancing the photovoltaic performances as well as the overall device stability.