Coordination Trap Induced Structural and Luminescent Property Transformation of Low Dimensional Organic‐Inorganic Hybrid Perovskites.

Herein, a coordination trap strategy is proposed for constructing stimulus‐responsive phosphorescent perovskites. Hydroxyl groups are selected as trap groups and introduced into benzylamine hydrochloride of Cd‐based perovskite. The resulting two‐dimensional (2D) perovskite (C7H10NO)2CdCl4·H2O (H1) exhibits blue fluorescence at 405 nm and green phosphorescence at 482 nm under 365 nm excitation. After introducing guest Mn2+, due to the passivation of defects, the doped H1 (H1‐M) achieves orange phosphorescence (λ = 615 nm) of Cd2+. Interestingly, because thermal stimulation induces the coordination of hydroxyl groups with metal ions, H1 and H1‐M are transformed into the zero‐dimensional (0D) perovskite (C7H10NO)2CdCl4 (H2) and doped H2 (H2‐M), respectively. The coordination immobilizes the organic molecules, thus resulting in a large increase in the phosphorescence lifetime and a strong green afterglow of H2. The coordination also transforms the luminescent center of the doped perovskite from the host metal ion of H1‐M to the guest metal ion of H2‐M, achieving red phosphorescence of Mn2+ at 685 nm. Under water vapor, H2 and H2‐M are reversibly converted to H1 and H1‐M, respectively. Based on the above phenomena, a multilevel anti‐counterfeit encryption system with water/heat stimulus‐response is developed, which provides a new idea for the design of stimulus‐responsive phosphorescent intelligent materials. [ABSTRACT FROM AUTHOR]