Highly Photoluminescent RGB-Carbon Dots and Their Integration Applications in Light-Emitting Diodes and Luminescent Solar Concentrators

Carbon dots (CDs) have emerged as a promising platform for constructing optoelectronic devices. However, the synthesis of multicolor CDs with high quantum yield (QY) and the elucidation of their luminescence mechanisms remain challenges. Here, we successfully synthesize RGB-CDs by precisely controlling the ratio of o -phenylenediamine and phytic acid. The QYs of the RGB-CDs are up to 60.3%, 68.7%, and 19.0%, respectively. Experimental data and DFT calculations reveal that the fluorescence emission of the RGB-CDs originates from molecule state (5,14-dihydroquinoxalino[2,3- b ] phenazine), carbon core state, and clusteroluminescence state induced by the through-space interactions of heteroatom groups, respectively. Moreover, leveraging the outstanding fluorescence properties of the RGB-CDs, we fabricate both a white light-emitting diode (WLED) with an ultra-high color rendering index of 98 and a luminescent solar concentrator achieving a high power conversion efficiency of 1.6%. Finally, we integrate a self-powered lighting system combining the WLED and LSC, which provides approximately 6 h of continuous illumination to a 0.1 W WLED after a single day's charging. Our results demonstrate a facile method for preparing multicolor CDs with high QYs, enabling their use as phosphor sources for various optoelectronic device applications.