Rewritable Photoluminescence and Structural Color Display for Dual‐Responsive Optical Encryption

Abstract Optical encryption using coloration and photoluminescent (PL) materials can provide highly secure data protection with direct and intuitive identification of encrypted information. Encryption capable of independently controlling wavelength‐tunable coloration as well as variable light intensity PL is not adequately demonstrated yet. Herein, a rewritable PL and structural color (SC) display suitable for dual‐responsive optical encryption developed with a stimuli‐responsive SC of a block copolymer (BCP) photonic crystal (PC) with alternating in‐plane lamellae, of which a variety of 3D and 2D perovskite nanocrystals is preferentially self‐assembled with characteristic PL, is presented. The SC of a BCP PC is controlled in the visible range with different perovskite precursor doping times. The perovskite nanocrystals developed in the BCP PC are highly luminescent, with a PL quantum yield of ≈33.7%, yielding environmentally stable SC and PL dual‐mode displays. The independently programmed SC and PL information is erasable and rewritable. Dual‐responsive optical encryption is demonstrated, in which true Morse code information is deciphered only when the information encoded by SCs is properly combined with PL information. Numerous combinations of SC and PL realize high security level of data anticounterfeiting. This dual‐mode encryption display offers novel optical encryption with high information security and anti‐counterfeiting.