Tunable Emission of Pb(II) and Sb(III) Codoped 2D Hybrid BDACdBr4 Metal Halides for Cryptographic Anticounterfeiting Applications

Organic–inorganic hybrid metal halides have attracted much attention due to their remarkable optoelectronic properties. However, two-dimensional (2D) hybrid BDACdBr4 (BDA is 1,4-butanediamine) metal halides exhibit poor luminescence due to the indirect band gap nature. Herein, we successfully prepared Pb2+- and Sb3+-codoped BDACdBr4 single crystals through a recrystallization method, resulting in a tunable emission color. Under ultraviolet light excitation, the emission color switched from cold white, white, and warm white to orange-red, resulting from the different color ratio of the intrinsic self-trapped exciton emission of Pb2+ and Sb3+ ions with an ns2 electron configuration. The photoluminescence decay demonstrated efficient energy transfer from the Pb2+ to Sb3+ ions with an increasing ratio of Sb3+/Pb2+ doping. Based on the tunable emission under 365/395 nm excitations, this material exhibits promising cryptographic anticounterfeiting application. This work provided a reference for tuning the optical performance of Cd-based metal halides through a metal ion-codoping strategy.