Ultra‐Flexible Perovskite Hydrogel Inspired by the Confined Nanogrowth in Biomineralization

ABSTRACT Perovskite hydrogels, as promising materials for soft optoelectronic devices yet suffer from poor stability. Inspired by the confined growth in biomimetic mineralization, we hereby present an ice‐confined strategy for the in ‐situ synthesis of perovskite nanocrystals in the hydrogel matrix, which shows an outstanding water‐proof photoluminescence. Moreover, the confined waters in the hydrogel matrix assist the formation of core–shell CsPbBr 3 @CsPb 2 Br 5 heterostructure, stimulating a narrowband photoluminescence (FWHM = 18 nm) with the quantum yield up to 99.86%. The robust CsPbBr 3 @CsPb 2 Br 5 Perovskite hydrogel (Pe‐gel) can be stretched with elongation up to 520% while maintaining the luminescent properties. Endowed by the superior luminescent behavior, both flexible light‐emitting diodes and X‐ray imaging based on the perovskite hydrogel have been constructed, demonstrating remarkable imaging resolution in wearable optoelectronic devices. Therefore, this work offers an efficient strategy to resolve the stability of perovskite‐based materials, and opens an avenue toward its applications in wearable display devices.