Energy‐Transfer‐Driven Programmable Luminescence in Bi 3+ ‐Eu 3+ Co‐Doped Na 3 Ca
Weiwei Xiang, Yuxiang Li, Jae Su YuABSTRACT
The energy‐transfer‐driven multifunctional luminescence behaviors of a novel Bi 3+ ‐Eu 3+ co‐doped Na 3 Ca 2 TaO 6 (NCTO) phosphor are systematically investigated. In the multi‐octahedral framework of the NCTO host, Bi 3+ ions act as broadband sensitizers while Eu 3+ ions serve as efficient red‐emitting centers, enabling effective non‐radiative energy transfer from Bi 3+ to Eu 3+ ions. Under ultraviolet excitation, the co‐doped system exhibits excitation‐dependent emission, while tunable emission is achieved by a combination of Bi 3+ broadband emission and Eu 3+ characteristic line emission. The energy‐transfer efficiency is confirmed to be governed by dipole‐dipole interactions. Furthermore, the distinct thermal responses of Bi 3+ and Eu 3+ emission centers give rise to a reliable fluorescence intensity ratio behavior based on non‐thermally coupled luminescence, enabling accurate temperature sensing with high fitting reliability. The flexible phosphor‐polydimethylsiloxane films are fabricated to realize multi‐mode optical information encryption based on excitation‐selective emission, demonstrating their potential usage for next‐generation muti‐functional photoluminescent materials.