Tuning the Structural Color of Perovskite Nanosheet/Polymer Nanocomposite Hydrogels by Adsorption of Alkyltrimethylammonium

Abstract

Mechanochromic structural‐color hydrogels are promising materials for sensing and display applications; however, simultaneous control of hue and brightness remains challenging. Here, we report a simple and effective strategy for tuning optical parameters by adsorbing alkyltrimethylammonium ions (CnTMA, where n denotes the number of carbon atoms in the alkyl chain) onto perovskite nanosheets embedded in a polymer network. CnTMA adsorption modulates the effective nanosheet thickness and its surface charge, depending on both the CnTMA concentration and alkyl‐chain length. Consequently, the maximum reflection wavelength (λmax) and reflectance intensity at λmax (Rmax) can be systematically tuned, yielding bright structural colors across the visible region. The hydrogels also exhibit robust mechanical toughness and pronounced mechanochromic responses. This work establishes a facile and generalizable route for engineering high‐performance structural‐color materials with potential applications in flexible mechanosensors and next‐generation photonic displays.