Mn-Doped M₂CdCl₄ (M = CH₃NH₃ ⁺, C₂H₈N⁺, and C₃H₁₀N⁺) Layered Hybrid Perovskite and Its Flexible Film Based on Simple Mechanochemical Synthesis

Layered hybrid perovskites show significant advantages in the field of optoelectronics. However, the low quantum efficiency and complex preparation methods limit their applications. In this work, we developed a series of perovskite powders with a two-dimensional (2D) layered structure of organic-inorganic hybrid metal halides M2CdCl4:x%Mn (M = CH3NH3+, C2H8N+, C3H10N+) via facile mechanochemical methods. The prepared manganese Mn-doped MA2CdCl4 produces orange emission at 605 nm under both 254 and 420 nm excitation, which originates from a dual excitation channel competition mechanism, and its excitation channel could be changed with the increase of Mn2+ ion concentration. Typically, MA(2)CdCl(4):20%Mn powder exhibits high photoluminescence quantum yield (PLQY) close to 90% at 605 nm due to the organic amine ions enlarging the Mn-Mn interlayer distances. In addition, we prepared MA(2)CdCl(4):x%Mn@PVA flexible films, which also exhibit good luminescence at 254 nm excitation and were unexpectedly found to have a better response to Cs+, which could be a candidate for anticounterfeiting applications.