Synergistic buried interfacial optimization and phase-composition regulation enable highly efficient Dion-Jacobson perovskite solar cells

Abstract

High-performance quasi-two-dimensional (Q-2D) perovskite solar cells (PSCs) are limited by buried interface defects and non-ideal phase composition. Here, we introduce glycine (Gly) into the SnO2 electron-transport layer (ETL), and find that Gly can act as a molecular bridge to modify the SnO2/perovskite buried interface. The carboxyl (−COOH) groups of Gly molecules can effectively coordinate with under-coordinated Sn4+ to passivate the oxygen vacancy defects of SnO2, and the amino (−NH2) groups can interact with under-coordinated Pb2+ in the perovskite layer, significantly suppressing trap-assisted nonradiative recombination. Furthermore, the Gly incorporation promotes the formation of large-n phases and simultaneously decreases the amount of n = 2-4 phases in the perovskite film, facilitating efficient electron transfer from n = 1 to large-n phases. As a result, the Q-2D PSCs employing SnO2-Gly ETL achieve an impressive champion power conversion efficiency (PCE) of 18.20% with improved shelf-life stability (ISOS-D-1). This study reveals the role of Gly as a molecular bridge to optimize the buried interface and achieve ideal phase composition for highly efficient Q-2D PSCs.