Highly efficient and photothermally stable CDs@ZIF-8 for laser illumination

Abstract

Carbon dots (CDs), as a solid-state phosphor, have great potential for application in a new solid-state lighting device—laser diode (LD). For high efficiency LD devices, both high photoluminescence quantum yield (PLQY) and high photothermal stability of CDs are essential. Herein, yellow CDs@ZIF-8 composites with high structural stability were prepared by encapsulating CDs in zeolitic imidazolate framework-8 (ZIF-8) through electrostatic adsorption between CDs and ZIF-8, in which CDs with amino groups on the surface were used as luminescent feeders and ZIF-8 was used as a protective layer matrix. The as-prepared CDs@ZIF-8 not only possess a high PLQY of up to 81.17%, but also maintain a high fluorescence intensity of 100% and 80% under long-term illumination (60 min) and high temperature (478 K), respectively. The hydrogen bonding between CDs and ZIF-8 in the encapsulated structure can enhance the degree of electron cloud delocalization, which can improve the PLQY of CDs@ZIF-8. Meanwhile, CDs@ZIF-8 has high photothermal stability due to the binding effect of ZIF-8 on CDs and high thermal stability of ZIF-8. The white LD device, fabricated from CDs@ZIF-8 as a phosphor in combination with 450 nm blue LD, has a color coordinate of (0.37, 0.33), a color temperature of 3762 K, and a high color rendering index of 86. This study provides a new strategy for the construction of solid-state phosphors with high PLQY and high photothermal performance.