Enhancing efficiency and stability of perovskite solar cells by introduction of triethanolamine

The presence of defects in the perovskite absorption layer significantly reduces the photovoltaic performance of perovskite solar cells (PSCs). In this study, a Lewis base Triethanolamine (TEA) is introduced on the perovskite surface, and the hydrogen bond formed by its hydroxyl group with Pb ions or I ions fix the halogen anion of perovskite and suppresses the migration of ions in perovskite. TEA has an obvious effect at the grain boundary, significantly improving the surface quality of the perovskite film and the device's efficiency. Compared with the pristine device (19.26%), the device after passivation at the optimal concentration exhibits better photovoltaic performance and stability, which obtained the champion efficiency of 20.39% and remained at 88.3% of the initial efficiency after being aged 1080 h without encapsulation. We expect that adding TEA to the perovskite surface will provide a useful strategy to enhance the performance of PSCs, as well as air and thermal stability.