pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2021; 71: 104-110

Published online February 26, 2021 https://doi.org/10.3938/NPSM.71.104

## The Ratio of NaBH$_{4}$ in the Synthesis of Water-soluble CdTe Nanocrystals

Il-gon KIM*, Dong-sun YOO

Department of Physics, Changwon National University, Changwon 51140, Korea

Correspondence to:dsyoo@changwon.ac.kr

Received: November 11, 2020; Revised: December 17, 2020; Accepted: January 5, 2021

### Abstract

The synthesis and the structural properties of CdTe quantum dots with high luminous efficiency were studied. Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and Raman spectra were measured to determine the structural characteristics of the synthesized samples. The Stokes shift for each sample was investigated using the absorption and the emission spectra from the three sample groups (S1, S2, S3) synthesized with NaBH$_{4}$/Te ratios of s 2, 5, and 10, the Stokes shift decreased with increasing heat-treatment time, but increased after a certain period of time. The CdS peak was seen at 300 cm$^{-1}$ in the Raman spectrum of the nanocrystals with a heat treatment time of 24 hours. From this observation, we were able to confirm that a CdS cell had been formed. The spectral ranges of the S1, S2, and S3 samples synthesized with different ratios were 500 ~ 540 nm, 620 ~ 690 nm, and 650 ~ 710 nm, respectively. The photoluminescence quantum yield of the sample group S2 with a NaBH$_{4}$ to Te ration of 5 was high, being 30 ~ 50%.

Keywords: CdTe/CdS, Core/shell, Raman