Interface Passivation with Codeposition Strategy toward High-Efficiency and Stable Perovskite Solar Cells

The interfaces of each layer in perovskite solar cells (PSCs) are critical factors for efficient and stable perovskite solar cells (PSCs). Especially, poor contact characteristics between perovskite and the electron transport layer in n-i-p-type PSCs significantly affect the carrier dynamics at the buried interface, hindering further improvement in the performance of devices. Herein, we propose a novel codeposition strategy based on (4-bromophenyl) phosphonic acid, which effectively passivates interface and improves the morphology of perovskites, achieving a power conversion efficiency of 24.9%. A part of the molecules spontaneously bond to tin dioxide and act as bridging molecules to connect the tin dioxide layer and perovskite layer during the absorber layer spin-coating process. The phosphonic acid groups and bromine atoms effectively fill oxygen vacancies in tin dioxide and halogen vacancies in the perovskite film. The deprotonated molecules passivate uncoordinated lead defects as passivating agents. The high-efficiency PSCs retained 81% of initial efficiency under ISOS-L-1 MPP tracking for 300h. This approach provides new insights into the interface passivation strategy to realize low-cost and efficient PSCs.