Perovskite solar cells using NaF additive with enhanced stability under air environment

In this study, we report a facile method to enhance the photovoltaic performance of solar cells based on carbon-counter-electrode by introducing NaF additives into the CH 3 NH 3 PbI 3 (MAPbI 3 ) film. The NaF additives can not only promote the crystallization of perovskite polycrystals but also help to form uniform, high-coverage, and high-quality perovskite films, leading to better light absorption and hydrophobicity. The device with addition of NaF has a maximum power conversion efficiency (PCE) of 11.26%, which is significantly higher than those without NaF (7.66%). Furthermore, the devices with the NaF additive exhibit superior stability, as they retained more than 95% of the original PCE after 2400 h in a humid atmosphere, which is considered to be associated with the presence of NaF and carbon electrode.