Carbon Dots Doped with N and S towards Controlling Emitting.

N-doped carbon dots (N-Cdots) were prepared via a solvothermal process in different solvents including water, acetone, and N,N-dimethylformamide (DMF). The red-shifted photoluminescence (PL) peaks and prolonged lifetimes were observed in the three excitation-independent samples. Considering that the similar size distribution, these variations of PL properties were mainly attributed to surface states of Cdots. The crucial effect of acetone and DMF as aprotic solvents were proposed because they can not provided hydrogen during the whole reaction process like H2O, and thus the dehydration reaction was accelerated. Much more N elements were introduced into N-Cdots. Except for N-doping, similar reaction were conducted when N and S were introduced into Cdots at the same time. Similar PL behaviour of N,S-co-doped carbon dots (N,S-Cdots) further confirmed above assumption. This work provided a simple method to control the PL behaviour of Cdots, which will have a promising future in the application of bioimaging and other fields.