Self-healing ion-conducting elastomer towards record efficient flexible perovskite solar cells with excellent recoverable mechanical stability

Abstract

Recently, self-healing polymers have been introduced into perovskite systems to repair the grain boundary cracks and interfacial delamination caused by bending and stretching cycles. However, self-healing polymers usually require external light, heat, and moisture stimuli to be active. In addition, self-healing polymers typically have poor electrical conductivity and are prone to forming insulated grain boundaries and interfaces, which will limit the effective extraction and transport of charge carriers. Herein, we designed a self-healing ionic conductive elastomer (ICE) containing imidazolium-based ionic liquids and incorporated it into perovskite films, which effectively repaired grain boundary cracks at room temperature (∼25 °C) and reduced the potential difference between the grains and grain boundaries of the films. The stable power conversion efficiency (PCE) of the ICE-containing rigid and flexible PSCs were 25.47% and 24.84%, which are the highest efficiencies reported among all flexible perovskite solar cells (PSCs). In addition, the corresponding devices maintained more than 90% of their initial efficiency after 5000 h in a N₂ glove box. Importantly, after 10 000 bending cycles (5 mm bending radius) of the ICE-containing flexible PSCs at room temperature (∼25 °C) for 1 h, the device performance can recover from 50% (before recovery: 12.43%) to 91% (after recovery: 22.59%) of the initial PCE (24.84%). This strategy will promote the development of flexible wearable electronics.