Construction of full-color light-emitting N-based carbon nanodots and their efficient solid-state materials via tape-casting technology for warm WLED

Multicolor luminescent carbon dots (Cdots) are of immense importance nowadays, while it still a challenge to construction of full-color light-emitting Cdots and their efficient solid-state materials. Here in, we fabricated a facile method to synthesize multicolor Cdots by adjustment of the reaction temperature. Although all samples showed uniform distribution of particles size and similar graphite structure, the surface chemical composition gradually varied among Cdots, especially the oxygen contents and nitrogen contents. Detailed material characterization has revealed that this tunable emission is results from the changes of the chemical composition. It is believed that the surface oxidation become more severe at high temperature, resulting in the formation of higher oxygen and nitrogen, which are responsible for the long-wavelength emission. Meanwhile, flexible solid-state materials were successfully created by combination of organosilane (OSi) and Cdots, which can be used to prevent the aggregation-induced solid-state fluorescence quenching. Finally, red Cdots/OSi was stacked on the Y 3 Al 5 O 12 :Ce 3+ (Ce 3+ : YAG) phosphor-in-glass (Ce-PiG) via tape-casting technology. Then, warm white light-emitting diodes (WLEDs) were constructed by these materials and GaN chips. As the Cdots increases, the correlated color temperature (CCT) decreases while the color rendering index (CRI) increases, and the color coordinates shift towards the red region. The resulting color converting material produced a warm white by adjusting red Cdots content, which will be a promising candidate for applications in the warm WLED.