Buried interface modification for high performance and stable perovskite solar cells†

Abstract

Defects at the buried interface between the perovskite film and electron transport layer (ETL) are detrimental for both the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). Herein, phenylhydrazinium chloride (PC) is designed as an effective passivation agent to significantly reduce defect density at the buried interface. It is found that the strong interaction between PC and PbI₂ not only passivates defects at the buried interface, but also retards the crystallization process of perovskite films, enabling high-quality perovskite films with low defects, resulting in improved PCE from 24.67% to 25.80% for small area devices and PCE up to 24.12% for large-area (1 cm²) ones. Additionally, the PCE of the flexible PSC (F-PSC) was improved to 24.54%, and both are among the highest in their respective categories. The excellent stability of the PSCs was also achieved, with 93.94% of the initial PCE retained after 1008 hours at 25 °C under 30% humidity. This paves a way for buried modification of perovskite films, large-scale preparation of PSCs, and fabrication of F-PSCs.