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.