Interfacial electrostatic repulsion inhibits iodide ion migration for enhancing reverse-bias stability of perovskite solar cells

The perovskite solar cells (PSCs) achieve notable advances in stability under humidity, light, and heat stress. However, PSCs are still susceptible to reverse-bias degradation, mainly due to the inevitable iodide ions migration. Herein, we reveal the irreversible cross-layer migration of iodide ion (I-) within PSCs under reverse bias, which contributes to the device performance failure. Further, we innovatively construct an electrostatic repulsion with I- at the perovskite interface, which can inhibit I- cross-layer migration under reverse bias in a nonbonding manner. Besides, the TFMS capable of blocking the hole injection can reduce the interface I- oxidation under reverse bias. The modified PSCs deliver efficiencies of 25.80% with TiO2 as the electron transport layer (ETL) and 26.21% (certification of 26.09%) with SnO2 as the ETL. More importantly, the device exhibit an enhanced reverse-bias stability by maintaining >80% of initial efficiency after 25 bias aging cycles (0 V/−1 V/0 V, each stage lasts for 12 hours). Our work provides a route to inhibit ion migration in PSCs and other perovskite-based devices through a novel interaction of electrostatic repulsion. Perovskite solar cells suffer from reverse-bias degradation due to inevitable migration of iodide ions. Here, the authors incorporate tetrabenzenesulfonic acid molecules at the perovskite interface to create an electrostatic repulsion with iodide ions, achieving maximum device efficiency of 26.21%