Tuning of photoluminescence in cadmium selenide nanoparticles grown in CTAB based quaternary water-in-oil microemulsions

Cadmium selenide nanoparticles were synthesized in cetyl trimethyl ammonium bromide (CTAB) microemulsion under ambient conditions and were found to be stable for months. The as-grown cadmium selenide nanoparticles exhibit strong room temperature photoluminescence with two emission peaks at 500 and 580 nm. The photo-excitation at wavelength above the exciton absorption peak gives rise to the sole band gap photoluminescence with the maximum at 500 nm whereas, the photo-excitation below the exciton absorption peak, furnishes only the trap state photoluminescence with the maximum at 580 nm. The photo-excitations at wavelengths closer to the exciton absorption peak give rise to both the emission peaks simultaneously. Intensities of these two emission peaks could be clearly tuned by controlling the precursor concentrations and the size of water pool in the microemulsions.