Buried Interface Strategies with Covalent Organic Frameworks for High-Performance Inverted Perovskite Solar Cells

Simultaneously controlling defects and film morphology at the buried interface is a promising approach to improve the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs). Here, two new donor‒acceptor type semiconductive covalent organic frameworks (COFs) are developed, COF_TPA and COF_ICZ. The carefully designed COFs structure not only effectively regulates the morphology and defects of the buried interface film, but also realizes the alignment with the energy level of the perovskite film and enhances the extraction and transmission of the interface charge. Among them, COF_ICZ-treated inverted PSCs achieved a maxmum PCE of 25.68% (certified 25.14%), the inverted PCE reached a minimum PCE of 22.92% for 1 cm² device. The efficiency of inverted PSCs with a 1.68 eV wide bandgap reached 22.92%, which is the highest datum of the reported 1.68 eV wide bandgap PSC. This lays the groundwork for the commercialization of perovskite/silicon tandem solar cells. Additionally, the unencapsulated devices demonstrated a high degree of stability during operational use and when subjected to conditions of high humidity and temperature.