Excitation-dependent persistent luminescence in CsCdCl3: Mn2+, Sb3+ phosphors for multi-dimensional optical encryption

Mn 2+ ,Sb 3+ co-doping enables excitation-dependent afterglow in CsCdCl 3 phosphors. • Mn 2+ ,Sb 3+ co-doping prolongs CsCdCl 3 afterglow compared with singly doped samples. • Multi-dimensional optical encoding based on excitation- and time-dependent afterglow enables dynamic anti-counterfeiting. Excitation-dependent persistent luminescence materials attract growing interest for optical encryption, as emission colour and decay behaviour enable multi-parameter information encoding. Achieving high brightness, stable afterglow over a wide temperature range, and controllable emission output within a single material system remains challenging. In this work, CsCdCl 3 : Mn 2+ , Sb 3+ phosphors are synthesized via a room-temperature solution method, which offers a simple and scalable route. The materials exhibit distinct afterglow responses under ultraviolet excitation at 254, 310, and 365 nm. Sb 3+ exhibit cyan emission originating from the 3 P 1 → 1 S 0 transition, while Mn 2+ gives rise to orange-red emission ( 4 T 1 ( 4 G) → 6 A 1 ( 6 S)), sensitized by energy transfer from Sb 3+ to Mn 2+ . The relative contributions of these emission centres vary with excitation wavelength. Excitation-dependent afterglow decay behaviour is therefore achieved. Thermoluminescence analysis reveals a quasi-continuous trap distribution. This distribution supports stable afterglow over a wide temperature range. It also determines the decay behaviour. Excitation-dependent trap filling causes variations in afterglow lifetime. Time-resolved luminescence output is achieved. These properties enable dynamic optical anti-counterfeiting. Information is encoded and decoded through excitation wavelength, emission colour, and afterglow duration. Multi-dimensional and time-dependent data display is realised. This work offers great potential for designing persistent luminescence materials for advanced optical encryption applications.