Khafajeh R, Molaei M, Karimipour M
Department of Physics, Faculty of Science, Vali-e-Asr University, Rafsanjan, Iran.
Luminescence. 2017 Jun;32(4):581-587. doi: 10.1002/bio.3224. Epub 2016 Oct 4.
In this study, ZnSe and ZnSe:Cu quantum dots (QDs) were synthesized using Na SeO as the Se source by a rapid and room temperature photochemical (UV-assisted) approach. Thioglycolic acid (TGA) was employed as the capping agent and UV illumination activated the chemical reactions. Synthesized QDs were successfully characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) and UV-visible (UV-vis) spectroscopy, Fourier transform-infrared (FT-IR), and energy dispersive X-ray spectroscopy (EDX). XRD analysis demonstrated the cubic zinc blend phase QDs. TEM images indicated that round-shaped particles were formed, most of which had a diameter of about 4 nm. The band gap of the ZnSe QDs was higher than that for ZnSe in bulk. PL spectra indicated an emission with three peaks related to the excitonic, surface trap states and deep level (DL) states. The band gap and QD emission were tunable only by UV illumination time during synthesis. ZnSe:Cu showed green emission due to transition of electrons from the Conduction band (CB) or surface trap states to the T acceptor levels of Cu . The emission was increased by increasing the Cu ion concentration, such that the optimal value of PL intensity was obtained for the nominal mole ratio of Cu:Zn 1.5%.
在本研究中，以亚硒酸钠为硒源，通过快速室温光化学（紫外辅助）方法合成了ZnSe和ZnSe:Cu量子点（QDs）。巯基乙酸（TGA）用作封端剂，紫外光照激活化学反应。使用X射线衍射（XRD）、透射电子显微镜（TEM）、光致发光（PL）和紫外可见（UV-vis）光谱、傅里叶变换红外（FT-IR）和能量色散X射线光谱（EDX）对合成的量子点进行了成功表征。XRD分析表明量子点为立方闪锌矿相。TEM图像表明形成了圆形颗粒，其中大多数直径约为4nm。ZnSe量子点的带隙高于块状ZnSe的带隙。PL光谱表明发射有三个峰，分别与激子、表面陷阱态和深能级（DL）态有关。带隙和量子点发射仅在合成过程中通过紫外光照时间进行调节。ZnSe:Cu由于电子从导带（CB）或表面陷阱态跃迁到Cu的T受主能级而呈现绿色发射。发射强度通过增加Cu离子浓度而增强，使得在Cu:Zn标称摩尔比为1.5%时获得PL强度的最佳值。
