Flexible, Stretchable, and Luminescent Hydrogels Based on a Polydimethylsiloxane-Coated CsPbBr₃ Nanostructure for Elastomers

Cesium lead halide perovskite nanocrystals (PNCs) have attracted great attention in optoelectronic devices due to their excellent optical properties, such as tunable emission wavelengths, long carrier lifetime, and narrow full width at half-maximum (fwhm). However, the poor stability of PNCs in water or humid environments greatly limits their wide-spreading applications. It is challenging to prepare PNCs with long-term stability in water. Herein, we successfully prepared CsPbBr 3 @PDMS microspheres by using the emulsification method. Due to the protection of the PDMS layer, the CsPbBr 3 @PDMS microspheres exhibit good optical properties and stability in water, acid, and alkali solutions. In addition, to expand the application of CsPbBr 3 NCs in flexible optical devices and wearable devices, we first prepared stretchable, stable, and photoluminescent hydrogel with a CsPbBr 3 @PDMS microsphere (hydrogel/CsPbBr 3 @PDMS) by using the emulsification method. The hydrogel/CsPbBr 3 @PDMS elastomer exhibits good stability and stretchability. Furthermore, the hydrogel/CsPbBr 3 @PDMS elastomer retains bright green emission and stability under different mechanical deformations. This work provides a method to improve the CsPbBr 3 PNCs with high stability by emulsification, which could also expand the applications of PNCs in underwater display, wearable, and flexible optoelectronic devices.