Steady state and time resolved spectroscopic study of C-dots–MEH–PPV polymer nanoparticles composites

Fluorescent carbon dots (C-dots) have been found to be a new class of nanomaterial for potential applications. Herein, polyethylenimine branched (BPEI) functionalized carbon dots (C-dots) are synthesized by changing the synthesis time using a microwave pyrolysis method. The photoluminescence intensity and average decay time of C-dots are found to be increased with increasing the crystallinity of the C-dots. C-dots–MEH–PPV polymer nanoparticles composites are formed by electrostatic interaction between these particles. The intensity of C-dots quenches dramatically with increasing the concentration of MEH–PPV nanoparticles (PNPs) and the intensity of PNPs increases gradually under excitation at 370 nm. This phenomenon may be due to energy transfer from C-dots to PNPs because there is a good spectral overlap between the emission spectra of C-dots and the absorption spectra of PNPs. The drastic photoluminescence quenching and the shortening of the decay time of C-dots in the composites confirms the efficient resonance energy transfer from C-dots to polymer nanoparticles. The energy transfer efficiency (66% to 89%) and rate of energy transfer are found to depend strongly on the time of pyrolysis. These C-dots–polymer composites will open up a way for developing new challenging materials for potential applications.