温度对CdSe/ZnS量子点吸收光谱和光致发光谱的影响

测量了分散于正己烷溶液和甲苯溶液中的CdSe/ZnS量子点在室温到近溶液沸点温度间的吸收与光致发光光谱,比较了两种不同的CdSe/ZnS量子点的光谱特性,讨论了温度对吸收和光致发光光谱峰值波长以及相对强度的影响。结果表明:在25~100℃范围内,CdSe/ZnS量子点激子吸收峰波长有微小红移,最大约为4nm;光致发光光谱峰值波长略有红移,但最大不超过6nm。根据光致发光光谱测量的结果,确定了Varshni定律中关于CdSe/ZnS量子点禁带宽度的两个经验参数:α=(2.0±0.2)×10^-4eV/K和β=(200±30)K。温度对CdSe/ZnS量子点吸收强度影响不大,荧光发射强度与温度呈线性关系增强。

Effect of the Temperature on Absorption and Photoluminescence Spectra of CdSe/ZnS Quantum Dots

The absorption and photoluminescence spectra of the CdSe/ZnS quantum dots dispersed in hexane and toluene solution are measured in different temperatures. Effect of the temperature on the absorption and photoluminescence spectra is discussed by comparing the spectral characteristics of two types of the CdSe/ZnS quantum dots. The measured results indicate that the absorption-peak wavelengths have a slight red shift (~4 nm) as the temperature increases, the photoluminescence-peak wavelengths having a little red shift, but no more than 6 nm as the temperature increases since 25℃ to 100℃. Two experiential coefficients in Varshni law regarding to bandgaps are determined at the first time according to the measured PL spectra of the CdSe/ZnS quantum dots. The measured abilities of the absorption show a little change with different temperatures, and photoluminescence intensities are proportional to the increase of the temperature.