A comparative study on impact factors of emission: surface state, carbonaceous core, and size based on series of exactly designed P, S co-doped carbon dots

Heteroatoms, such as nitrogen, sulfur, and phosphorus, in surface state dedicate the passivation layer, which along with the structure of carbonaceous core (the size of conjugated sp² domains) and diameter in carbon dots affect the emission. To disclose the dominant one among them, two series of well-designed P, S co-doped carbon dots (P/S-CDots) possessing different particle sizes and individual chemical structures both in surface and core were prepared. As results, the concentration of sp² hybrid carbon atom in carbonaceous core plays the vital role in effecting the photoluminescence efficiency of carbon dots by determining the optical-harvesting ability, followed by heteroatom's doping amount. Besides, phosphorus is superior to sulfurs regarding to improving the photoluminescence efficiency based on the calculated results of LUMO-HOMO gap. It is worth mentioning that the copolymer as precursor is very qualified in the paper, because that the structure and diameter of P, S-CDots are easy to be manipulated by managing the chain structure and molecular weight of it, which is a terpolymer prepared by free radical polymerization using acrylic phosphate, sodium methylallyl sulfonate, and acrylic acid as monomers in the presence of ammonium persulfate. .