Polymer types regulation strategy toward the synthesis of carbonized polymer dots with excitation-wavelength dependent or independent fluorescence

Three kinds of carbonized polymer dots (CPDs) synthesized via a one-pot process from o-phenylenediamine (OPD), m-phenylenediamine (MPD) and p-phenylenediamine (PPD) exhibit excitation-wavelength independent yellow, green and red emissions, respectively. In sharp contrast, two kinds of CPDs prepared via a hydrothermal process from citric acid (CA) and diethylenetriamine (DETA) exhibit obvious excitation-wavelength dependent emissions. Through the characterization and comparison of the two types of CPDs, it is concretely revealed that the polymer structure types during the formation of CPDs can effectively control the fluorescence excitation-wavelength independence/dependence. The homogeneous polymer structures contained in CPDs contribute to excitation-wavelength independence, whereas random copolymer structures contribute to excitation-wavelength dependence. These studies are of great significance for further understanding the polymer structures and designing unique optical properties of CPDs.