Synthesis of cubic CdSe nanocrystals and their spectral properties

Yukun Gao,Pg Yin

doi:10.1177/1847980417701747

Abstract

The cadmium selenide nanocrystals are prepared by colloidal chemistry under mild conditions. X-ray diffraction and high-resolution transmission electron microscopy measurements indicate that as-prepared cadmium selenide nanocrystals are zinc blende cubic structure. We carry out an analysis of quantum size effect in the Raman spectra of cadmium selenide nanocrystals performed by utilizing the chemical bond theory of Raman peak shift developed recently. It is revealed that the shifts of Raman peaks in cadmium selenide nanocrystals result from the overlapping of the quantum effect shifts and surface effect shifts. The sizes of the as-prepared cadmium selenide nanocrystals obtained by employing the Raman peak shift theory are in good agreement with the nanocrystal sizes determined by high-resolution transmission electron microscopy.

Highlights

In the past decade, photoluminescent colloidal cadmium selenide (CdSe) nanocrystals have drawn much attention due to their promising applications in light-emitting diodes, living cells’ fluorescent labels, photovoltaic devices and so on
When the nanocrystals are small compared to the exciton Bohr radius (5.4 nm) of CdSe nanocrystals, interesting size-dependent optical properties arise in CdSe nanocrystals
The High-resolution transmission electron microscopy (HRTEM) observation (JEOL-JEM 2010 operated at 200 kV) show the spacing between adjacent lattice planes is about 0.35 nm, corresponding to the distance between (111) planes of zinc blende CdSe nanocrystals

Summary

Introduction

Photoluminescent colloidal cadmium selenide (CdSe) nanocrystals have drawn much attention due to their promising applications in light-emitting diodes, living cells’ fluorescent labels, photovoltaic devices and so on. Many literatures are available on relatively large CdSe nanocrystals, while reports on smaller CdSe nanocrystals are relatively in deficiency.[6,7] For typical crystalline CdSe, Raman spectral features of nanocrystals were considerably different from the corresponding pattern and features.[8,9] Studies on the vibrational properties of nanocrystals are focused on an understanding of the fundamental physical properties of strongly confined phonons.[10,11,12,13]

Methods

Results

Conclusion