Exceeding 67.35% Efficient and Color Temperature Tunable White Light from Carbon Dots with Quadruple-Channel Fluorescence–Phosphorescence Emission
Jian Shen, Bin Xu, Shunwei Chen, Yuehan Jia, Jie Li, Tianlong Jiang, Zhenhua Gao, Xue Wang, Chaofeng Zhu, Hui Shi, Zifei Wang
Abstract
Luminescent carbon dots (CDs) have drawn much attention in terms of photoelectronic applications, most of which are focused on single-component white-light emission. However, it still remains a significant challenge to create high-quality white-light-emitting CDs with tunable correlated color temperatures (CCTs). The theoretical calculation is initially used to predict that the enlargement of the conjugated sp2 domain induces redshift fluorescence (FL) and room temperature phosphorescence (RTP) emissions of CDs. Guided by the theoretical predictions, single-component white-light emission from CDs with high efficiency of 67.35% and tunable CCTs from 10,803 to 3376 K is realized. These CDs exhibit quadruple-model emissions with hybrid FL/RTP components at 435 nm (FL-1)/548 nm (RTP-1) and 461–522 nm (FL-2)/525–610 nm (RTP-2), which originate from a synergy between certain P bonds with aggregation-induced emission effects and different sizes of sp2 conjugated structures, respectively. Using such CDs as conversion phosphors, we prepared three white-light-emitting diodes (WLEDs) which can emit bright cool, standard, and warm white lights with color rendering indices of 81–85. Finally, highly luminescent WLEDs are also developed by dispersing these CDs in a poly(vinyl alcohol) matrix, indicating that this provides an industrial application potential.