Water‐Operable Photochromic Perovskite‐Like Materials for Rewritable Anti‐Counterfeiting and Display

ABSTRACT Stimuli‐responsive solid‐state photochromic materials are attractive for information encryption and smart displays, yet purely organic systems often suffer from high water solubility, while fully inorganic counterparts are constrained by cost‐effective and scalable fabrication. These limitations highlight the challenge of developing water‐stable, water‐operable photochromic materials for underwater information writing and wet‐environment anti‐counterfeiting. Herein, we report a water‐stable 1D perovskite‐like lead chloride hybrid, (AeBpy) 2 Pb 3 Cl 10 , constructed with a viologen‐based organic dication (AeBpy 2+ : N ‐(2‐aminoethyl)‐4,4′‐bipyridinium). The structure features a negatively charged 1D inorganic backbone electrostatically balanced by AeBpy 2+ , a structural motif characteristic of low‐dimensional organic–inorganic perovskite‐like materials. Upon light irradiation, efficient photoinduced electron transfer enables rapid photochromism, with coloration occurring within 10 s and complete thermal decoloration achieved at 160°C within 10 min, supporting robust photo‐writing/erasing cycles. Importantly, the photochromic response remains operable directly in water, enabling aqueous information writing and on‐demand thermal erasing. This work provides a viable materials design strategy to address the challenge of water‐stable and water‐operable photochromic systems, enabling underwater information writing, wet‐environment anti‐counterfeiting, and rewritable displays.