Sub‐Micrometer Ag Particles Boost Luminescence and Thermal Stability of Perovskite Quantum Dot Phosphors for Light‐Emitting Diodes

ABSTRACT Perovskite quantum dots (QDs) have been considered as promising emitters for lighting and display applications, but they suffer from poor thermal stability under operation. Herein, we introduce sub‐micrometer Ag particles to simultaneously enhance the luminescence intensity and thermal stability of perovskite QDs. The CsPbBr 3 /Ag (CPB/Ag) hybrid phosphors are synthesized via an in situ solid‐phase method. We find that nano‐sized Ag particles quench perovskite QD emission, and their discontinuous structure also disrupts thermal conduction pathways, thereby sacrificing the benefit of metal particles. Relatively, sub‐micrometer Ag particles enable the hybrid phosphors a 2.2‐fold increase in PL intensity compared to pristine CsPbBr 3 by leveraging the strong light scattering. Furthermore, benefitting from the high thermal conductivity of sub‐micrometer Ag particles, the hybrid phosphors retain 75.6% of their initial PL intensity at 85°C, significantly higher than that of 24.8% for pristine CsPbBr 3 . As a result, a CPB/Ag‐based white LED (WLED) retains 83.5% of its initial luminance after 1000 h of operation, which is much higher than that of 30.3% for a pristine CsPbBr 3 ‐based WLED. This study demonstrates the crucial role of sub‐micrometer Ag particles in enhancing the brightness and thermal stability of perovskite phosphor and their potential for enabling reliable, high‐performance WLEDs.