Reshaped buried interface by comprehensive passivation for highly efficient perovskite photovoltaics

Defect passivation emerges as a potent approach to enhance the performance of perovskite solar cells (PSCs). In particular, the buried interface shows a higher defect density than the upper one. Despite recent growth in buried interface passivation studies, it remains less mature than upper interface or precursor doping passivation, possibly hindering imminent efficiency breakthroughs. In addition, most of the recent buried passivation work passivates only one or two kinds of defects, the remaining defects at the buried interface will still damage the performance of PSCs. Herein, a chlorine-rich ammonium salt named chloroacetamidine hydrochloride (CAHC) is selected to achieve comprehensive passivation of the buried interface. CAHC effectively addresses various defects in tin oxide (SnO2) and perovskite at the buried interface, significantly boosting the performance of PSCs. The power conversion efficiency (PCE) of the device based on CAHC modification reaches 24.78%. This work showcases promising advancements in buried interface passivation, offering a pathway for future breakthroughs in the performance of PSCs.