Carbon dots optimize the luminescence and morphological of Tm3+ doped zinc borate composites for NUV-WLEDs.

• A series of ZBH:Tm3+/yNCDs composites were synthesized by the hydrothermal method. • The ZBH:Tm3+/yNCDs could suppress the self-quenching effect of yNCDs in state solid. • The yNCDs improve the luminescence performance of ZBH:Tm3+ materials. • The influences of yNCDs on the structure, morphologies and luminescence properties of the composites were studied. • The tunable white light were achieved under 360 nm excitation. Rare earth (RE)-doped luminescent materials have shown tremendous potential applications in the optical field. However, it is still a challenge to improve its luminescence properties further. In this study, the Tm3+-doped zinc borate (4ZnO·B 2 O 3 ·H 2 O, ZBH) with a flaky-like morphology was successfully prepared by a facile hydrothermal reaction. The photoluminescence (PL) performance of ZBH:Tm3+ is improved through incorporating yellow N-doped carbon dots (yNCDs). Simultaneously, by changing the content of yNCDs in ZBH:Tm3+ host, the morphological evolution from flaky-like to flower-like of the ZBH:Tm3+/yNCDs composite are realized. The ZBH:Tm3+/yNCDs composite with flower-like exhibits the strongest white light emission and splendid thermal stability under 360 nm excitation wavelength, matching the current mainstream near-ultraviolet (NUV) LED chip. Thus, ZBH:Tm3+/yNCDs composite might be a promising luminescent material in the NUV white lighting and display fields. The findings of this study developed a novel idea for improving the luminescent properties of RE-doped materials. Besides, it also solves fluorescence quenching problems of carbon dots in the solid-state illumination field. [ABSTRACT FROM AUTHOR]