Multiple-Defect Management for Efficient Perovskite Photovoltaics

Abstract

A variety of defects exist on the crystalline surfaces of solution-processed polycrystalline perovskites, resulting in photovoltaic output losses and subsequent degradations. It is necessary to develop a versatile passivator that can concurrently eliminate multiple defects, including vacancy, interstitial, antisite substitution, and dissociative I2. Herein, we focus on multiple-defect management to optimize defective perovskite surfaces by using three kinds of chemical bonds with a pyridine-containing polymeric agent. Coordination bonds alleviate the distorted PbIx octahedrons by digesting I vacancies, and hydrogen bonds stabilize ammonium cations to eliminate organic vacancies and deep-level antisite defects. Furthermore, the dissociated I2 acting as electron traps from the coupled I interstitials could be blocked by supramolecular halogen bonds. Based on the low-defect perovskite films, substantial increases in photovoltaic efficiencies, going up to 22.02% and 23.14%, are achieved in planar and mesoporous devices, respectively, with nonencapsulated cells retaining 90% of their original efficiencies after 2200 h of aging in ambient conditions.