Physical investigation of ZnSe QDs synthesized by polyol method at 200 A°C

In this paper, zinc selenide nanoparticles powder was successfully synthesized using rapid polyol method. The preparation method was changed by using new Se solvents in the final stage to delete seleniums which have not participated in reaction product. This change in the preparation method increased the purity of final product (92 %); and using selenium's solvents as detergents caused the production of ZnSe with roughly 100 % purity. X-ray diffractions showed that the samples had a cubic structure with lattice constant equalling 5.6699 and with 5.5 nm for crystallite size. Atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) images showed that the particles were almost spherical and well crystallized ZnSe nanoparticles were formed. The average sizes of nanoparticles were 15 and 16.4 nm for AFM and HRTEM, respectively. Absorption Spectra of all samples showed a blue shift in comparison with bulk ZnSe. It showed low absorption in a wide range of wavelengths. Band gap energy of the pure ZnSe nanoparticles was found to be 4.51 eV, which is higher than that of the bulk value of ZnSe (2.67 eV). Photoluminescence spectra of the samples showed emission at 450-500 nm wavelengths at room temperature which are useful for the application of solar cells, quantum dot light-emitting diodes and blue organic light-emitting diodes devices.