Light-emitting graphene quantum dots (GQDs) are widely investigated due to their distinct merits. However, GQDs generally suffer from aggregation-induced luminescence quenching, which means they are highly emissive in a solution state with uniform dispersion but dramatically quenched in a solid or aggregated state. This problem significantly limits the application of GQDs, partially in the solid-state light-emitting devices. In this report, we successfully developed a simple and efficient hydrothermal method for the production of nitrogen doped graphene quantum dots (N-GQDs) with strong solid-state fluorescence (SSF) by using citric acid and o-Phenylenediamine as precursors. Under the 365 nm UV light illumination, the produced N-GQDs in an aqueous state exhibit blue color, with a quantum yield of 58%. As the concentration of N-GQDs increases, the photoluminescence exhibits an obvious red-shift from blue to yellow. For the N-GQDs in solid state, yellow luminescence with a high photoluminescence quantum yield (PLQY) of 28% is achieved under the 405 nm excitation. Finally, via the simple adjustment of thickness and the concentration of N-GQDs in blue emitting InGaN chips, color converter is enabled by constructing white light-emitting diode (WLED) device with improved color rendering index (CRI) and correlated color temperature (CCT).

发光石墨烯量子点（GQD）由于其独特的优点而被广泛研究。然而，GQD通常遭受聚集诱导的发光猝灭，这意味着它们在溶液状态下具有均匀分散的状态下高发射，而在固态或聚集状态下则显着淬灭。这个问题极大地限制了GQD的应用，部分地将其应用于固态发光器件中。在本报告中，我们成功开发了一种简单有效的水热方法，以柠檬酸和邻苯二甲胺为前体来生产具有强固态荧光（SSF）的氮掺杂石墨烯量子点（N-GQDs）。在365 nm紫外线照射下，生成的N-GQD呈水态，呈蓝色，量子产率为58％。随着N-GQDs浓度的增加，光致发光表现出从蓝色到黄色的明显红移。对于固态的N-GQD，在405 nm激发下可实现具有28％的高光致发光量子产率（PLQY）的黄色发光。最后，通过简单调整发射蓝光的InGaN芯片中N-GQD的厚度和浓度，可以通过构造具有改善的显色指数（CRI）和相关色温（CCT）的白光发光二极管（WLED）器件来实现颜色转换器。 ）。