Multiphonon Relaxation Inhibition and Photon Cutting Multiplication in Cs2NaYCl6: Ho3+/Er3+ for Information Encryption and NIR Bioimaging

The perovskite-based multifunctional integrated light-emitting platform has garnered significant attention due to the ultralow phonon energy and flexible lattice plasticity. Achieving both high-efficiency multiband light emission and excellent thermal stability for extreme conditions remains a critical challenge in system design and performance regulation. Herein, Ho 3+ and Er 3+ co-doped Cs 2 NaYCl 6 crystals suppress multiphonon relaxation, enabling precise control of the cross-relaxation between ions, thereby achieving mutual sensitization and multicolor visible fluorescence. Simultaneously, a parallel near-infrared (NIR) channel is activated through quantum cutting, where a high-energy photon is converted into two NIR photons via successive resonant energy transfer from Ho 3+ to Er 3+ , achieving a high internal quantum yield of 147.6%. Notably, the material exhibits high thermal sensitivity and exceptional anti-thermal quenching, with a luminescence intensity of 145.0% at 433 K relative to that at 313 K, showcasing tremendous potential for high-temperature optical sensing. The dynamic multicolor luminescence and highly efficient NIR emission are successfully integrated through a dual-channel luminescence mechanism, which establishes a multidimensional platform for optical encryption and bioimaging based on multifunctional luminescent system and high thermal stability, providing an innovative strategy for developing high-security anti-counterfeiting and deep tissue imaging.