Vacuum‐Boosting Precise Synthetic Control of Highly Bright Solid‐State Carbon Quantum Dots Enables Efficient Light Emitting Diodes

Abstract Carbon quantum dots (C‐dots) have emerged as efficient fluorescent materials for solid‐state lighting devices. However, it is still a challenge to obtain highly bright solid‐state C‐dots because of the aggregation caused quenching. Compared to the encapsulation of as‐prepared C‐dots in matrices, one‐step preparation of C‐dots/matrix complex is a good method to obtain highly bright solid‐state C‐dots, which is still quite limited. Here, an efficient and controllable vacuum‐boosting gradient heating approach is demonstrated for in situ synthesis of a stable and efficient C‐dots/matrix complex. The addition of boric acid strongly bonded with urea, promoting the selectivity of the reaction between citric acid and urea. Benefiting from the high reaction selectivity and spatial‐confinement growth of C‐dots in porous matrices, in situ synthesize C‐dots bonded can synthesized dominantly with a crosslinked octa‐cyclic compound, biuret and cyanuric acid (triuret). The obtained C‐dots/matrix complex exhibited bright green emission with a quantum yield as high as 90% and excellent thermal and photo stability. As a proof‐of‐concept, the as‐prepared C‐dots are used for the fabrication of white light‐emitting diodes (LEDs) with a color rendering index of 84 and luminous efficiency of 88.14 lm W −1 , showing great potential for applications in LEDs.