Orange emissive N-doped carbon dots and their application in detection of water in organic solvents and the polyurethane composites

In this work, efficient orange emissive N-doped carbon dots (N-CDs) were synthesized through a facile one-step solvothermal route using 1,4-phenylene diisocyanate as the only raw precursor. The as-prepared N-CDs exhibited strict excitation independent luminescence with a maximum emission peak at 581 nm. The absolute photoluminescence quantum yield was up to 38%. A reasonable formation process of N-CDs was explored in detail. Interestingly, the N-CDs was sensitive to water and thus, could be exploited as an excellent fluorescent probe directly for quantitative detection of water in organic solvents. Moreover, various orange-emitting N-CDs/polymer composites were achieved by simply incorporating the N-CDs into different polymer matrices. The N-CDs could be better uniformly dispersed in polyurethane (PU) matrix through the in situ polymerization technique, and the emission intensity of N-CDs/PU composite films could be linearly modulated by changing the N-CDs concentration. These investigations broaden promising application potentials of CDs in sensor and optoelectronic devices.