Efficient Passivation with Lead Pyridine-2-Carboxylic for High-Performance and Stable Perovskite Solar Cells

Stability has become the main obstacle for the commercialization of perovskite solar cells (PSCs) despite the impressive power conversion efficiency (PCE). Poor crystallization and ion migration of perovskite are the major origins of its degradation under working condition. Here, high-performance PSCs incorporated with pyridine-2-carboxylic lead salt (PbPyA(2)) are fabricated. The pyridine and carboxyl groups on PbPyA(2) can not only control crystallization but also passivate grain boundaries (GBs), which result in the high-quality perovskite film with larger grains and fewer defects. In addition, the strong interaction among the hydrophobic PbPyA(2) molecules and perovskite GBs acts as barriers to ion migration and component volatilization when exposed to external stresses. Consequently, superior optoelectronic perovskite films with improved thermal and moisture stability are obtained. The resulting device shows a champion efficiency of 19.96% with negligible hysteresis. Furthermore, thermal (90 degrees C) and moisture (RH 40-60%) stability are improved threefold, maintaining 80% of initial efficiency after aging for 480 h. More importantly, the doped device exhibits extraordinary improvement of operational stability and remains 93% of initial efficiency under maximum power point (MPP) tracking for 540 h.