25.24%-Efficiency FACsPbI 3 Perovskite Solar Cells Enabled by Intermolecular Esterification Reaction of DL-Carnitine Hydrochloride.

Judicious tailoring the interface between SnO 2 electron transport layer (ETL) and perovskite buried surface plays a pivotal role in obtaining highly efficient and stable perovskite solar cells (PSCs). Herein, a DL-Carnitine hydrochloride (DL) is incorporated into perovskite/SnO 2 interface to suppress defect-states density. A DL-dimer is obtained at interface by an intermolecular esterification reaction. For the SnO 2 film, the Cl - in DL-dimer can passivate oxygen vacancies (V o ) through electrostatic coupling, while N in DL-dimer can coordinate with the Sn 4+ to passivate Sn-related defects. For the perovskite film, the DL-dimer can passivate FA + defects via hydrogen bond and Pb-related defects more efficiently than DL monomer. Upon the DL-dimer modification, the interfacial defects are effectively passivated and the quality of the resultant perovskite film is improved. As a result, the DL-treated device achieves a gratifying open-circuit voltage (Voc) of 1.20 V and a champion PCE of 25.24%, which is a record value among all the reported FACsPbI 3 PSCs. In addition, the unencapsulated devices exhibit a charming stability, sustaining 99.20% and 90.00% of their initial PCEs after aging in air for 1200 h and continuously operating at the maximum power point (MPP) tracking for 500 h, respectively. This article is protected by copyright. All rights reserved.