Interlayer reinforcement for improved mechanical reliability for wearable perovskite solar cells

Abstract

Flexible perovskite solar cells (F-PSCs) are emerging as a promising solution for weight-sensitive, wearable, portable, and flexible applications. However, F-PSCs still suffer from poor mechanical reliability due to weak interlayer adhesion and stress mismatch. In this study, we present a successful approach using a polyacrylamide (PAM) interlayer at the buried interface to alleviate interfacial stress mismatch, enhance interfacial adhesion for mechanical stress dissipation, and regulate perovskite crystallization dynamics. The phase transition from the non-perovskite δ-phase to the perovskite α-phase, from the buried interface to the bulk film, was observed using in situ grazing-incidence wide-angle scattering (GIWAXS), which synergistically improves film quality and charge extraction. We achieved solar cells with efficiencies of 24.83% for a 0.06 cm² cell (certified 24.41%) and 17.46% for a 20 cm² module, with an exceptional specific power density of 1745 W kg⁻¹, all of which are among the highest in their respective categories. Importantly, the resulting devices exhibit significantly improved mechanical reliability under six types of stress conditions in real-world scenarios, maintaining 95% efficiency after 7000 bending cycles. This improved mechanical reliability is attributed to the enhanced stress dissipation ability, which helps maintain structural integrity and charge extraction, as evidenced by GIWAXS mappings and photocurrent imaging mappings.