One pot synthesis, growth mechanism and optical properties of Zn1−xCdxSe graded core/shell and alloy nanocrystals

Abstract

Comparatively higher photoluminescence yield along with robustness of core/shell semiconductor nanocrystals make them attractive candidates for studying intricate quantum size effects. Here, we report, one pot synthesis of Zn1−xCdxSe graded core/shell structures by exploiting change in the reactivity of precursors. Optical and structural measurements indicate formation of graded structure. Growth mechanism probed by inductively coupled plasma atomic emission spectroscopy shows formation of graded core/shell structure, with CdSe rich core and ZnSe rich shell. Annealing these nanocrystals, in chemical bath, leads to diffusion of Cd from core to shell region. Formation of Zn1−xCdxSe alloy is also observed in X-ray photoelectron spectroscopic measurements, confirming the diffusion of Cd from core to shell region. Substantially high photoluminescence quantum efficiency of 60% with narrow line width of about 27nm, was observed and is attributable to the reduced strain due to graded core/shell structure.