Porous Organic Cage Induced Spontaneous Restructuring of Buried Interface Toward High-Performance Perovskite Photovoltaic

In perovskite solar cells (PSCs), the buried interface containing high concentrations of defects is critical for efficient charge extraction toward high-performance device. Herein, porous organic cage (POC) is introduced between tin dioxide and perovskite to spontaneously reconstitute the buried interface. Through the chemical linkage formed by polydentate chelation of POC with SnO2 and perovskite, the buried interface achieves greatly reduced defect density and enhanced carrier extraction. More importantly, it is found that iodide ions in aged devices to migrate down to the electron transport layer and even invade the ITO electrode, changing the work function of ITO. This detrimental effect can be well resolved by POC since the host-guest interaction of POC can effectively suppress the iodide ions trying to migrate downward. As a result, the PSC fabricated by POC-restructured strategy yields a superior PCE of 24.13%. Moreover, the unencapsulated PSCs exhibit conspicuous improved long-term stability and retain 93% of its initial efficiency after 5000 h in ambient condition.