Stable Mn-Doped CsPbCl₃ Nanocrystals inside Mesoporous Alumina Films for Display and Catalytic Applications

Doping Mn²⁺ in CsPbCl₃ nanocrystals (NCs) has generated exciting optical properties, making it a potential candidate for illumination and display applications. Also, it opens up a way to substitute toxic Pb²⁺ partially by Mn²⁺. Herein, a mesopore-mediated pathway has been investigated toward the generation of Mn-doped CsPbCl₃ NCs inside the alumina thin film. Bottle-neck-shaped mesopores acting as “nanopots” provide an ideal confined environment for the synthesis to occur at room temperature and an ambient atmosphere. The Mn/Pb molar ratio has been deliberately kept less than 1 to examine the extent of doping within that limit, and a maximum of 29.4% substitution of Pb by Mn has been achieved. The role of mesopores, solvents, and precursor incorporation sequences in the synthetic procedure has been investigated in detail along with the properties of the composite film. Bright orange stable luminescent coating on large-area flexible plastic substrates has been developed with this room temperature, ambient atmosphere synthetic protocol. This strategy can be extended further toward doping of other metals or generation of non-Pb perovskite NCs and their doped counterparts, preferably at ambient conditions. Enhanced heat and photostability of the composite films compared to the solution-processed Mn/CsPbCl₃ NCs makes them suitable for display applications. Apart from that, because of the improved aerobic and moisture stability, this Mn/CsPbCl₃ NC mesoporous alumina composite film can act as the heterogeneous catalyst in chemical reactions, and here, as a proof of example, reduction of p-nitrophenol using sodium borohydride has been demonstrated.