Light‐Programmable 3D Device Study in Halide Perovskite‐Based Photochromic Conjugate

Abstract Recently, metal halide perovskite is a kind of emerging optoelectronic materials. However, their stability is a major challenge for practical application. Integrating perovskite composites with industrial polymer processing (e.g., 3D printing, melt electrospinning) not only improves their stability but also offers strong potential for advancing lab‐scale materials to commercial applications and more, bridging the gap to market‐ready solutions. A fluorescence resonance energy transfer (FRET) system is constructed by a solvent‐free twin‐screw blending method embedding CsPbBr 3 /spiropyran into polylactic acid/poly(butylene‐adipate‐co‐terephthalate (PLA 8 /PBAT 2 ), which can graft on the subsequent process, including 3D printing and melt electrospinning. As a result, various 3D devices based on CsPbBr 3 /SP@PLA 8 /PBAT 2 (CSPP0.5) composite are fabricated with improved stability of CsPbBr 3 . CSPP0.5 has reversible luminescence switching (green‐red) under UV and visible light pre‐irradiation, which is due to FRET between CsPbBr 3 and the open‐loop form of spiropyran (MC). This mechanism is unequivocally confirmed through fluorescence lifetime and femtosecond transient absorption (Fs‐TA) measurements. The photo‐responsive property endows CSPP0.5 with light‐programmable 3D devices for dynamic multi‐level anti‐counterfeiting encryption.