圆偏振光诱导CdTe量子点再生长及其对光致发光的影响

doi:10.15541/jim20170124

摘要/Abstract

摘要：

实验研究了以3-巯基丙酸为配体合成的水溶性CdTe量子点经过非偏振光与圆偏振光照射处理后, 量子点的再生长变化规律。采用光致发光谱、紫外-可见吸收光谱、透射电子显微镜与X射线衍射等表征手段分析表明: 非偏振光会促进CdTe量子点的光氧化, 导致量子点尺寸缩小, 荧光发光峰位蓝移, 且发光效率降低; 而圆偏振光增强了配体的光氧化, 在量子点表面形成CdS层, 导致量子点尺寸进一步增大, 荧光发光峰红移, 且发光效率提升。进一步讨论了CdTe量子点与配体之间的键合作用, 相关光化学反应机制及其对量子点光致发光性质的影响。

关键词: 碲化镉, 量子点, 光致发光, 偏振光调制

Abstract:

The water soluble CdTe quantum dots were synthesized in aqueous solution using 3-mercaptopropionic acid as stabilizer reagent. Effects of non-polarized and circular polarized light modification on structural and optical properties of quantum dots were investigated by photoluminescence spectroscope, ultraviolet visible absorption spectroscope, transmission electron microscope, and X-ray diffraction. It is revealed that the non-polarized light tends to oxidize the quantum dots, which brings about photo degradation of quantum dots and blue shift of photoluminescence. By contrast, the circular polarized light oxidizes the stabilizer reagent at the surface of CdTe quantum dots, which leads to regrowth of quantum dots and red shift of photoluminescence. Moreover, the photochemical reaction mechanism together with the bonding effect between stabilizer reagent and CdTe quantum dot were studied. The photoluminescence of CdTe quantum dot is associated with its surface states.

Key words: CdTe, quantum dots, photoluminescence, polarized-light modification

中图分类号:

O613

鄢波, 彭泽洋, 吕斌, 刘薇. 圆偏振光诱导CdTe量子点再生长及其对光致发光的影响[J]. 无机材料学报, 2017, 32(12): 1321-1326.

YAN Bo, PENG Ze-Yang, LV Bin, LIU Wei. Regrowth of CdTe Quantum Dots Induced by Circular Polarized Light and Its Effect on the Photoluminescence[J]. Journal of Inorganic Materials, 2017, 32(12): 1321-1326.

图/表 4

图1 不同回流时间的CdTe量子点的紫外-可见吸收光谱(a)和(b)光致发光谱, 回流18 h的CdTe量子点的XRD图谱, 插图为HRTEM高分辨透射电镜照片(c)和TEM透射电镜照片(d)

Fig. 1 U-Vis absorption spectra (a) and PL spectra (b) of CdTe QDs-524, QDs-598 and QDs-618; XRD pattern (c) and TEM image (d) of CdTe QDs-618 with inset displaying HRTEM image of the sample

图2 (a)圆偏振光和非偏振光源构造示意图, (b)圆偏振光照处理促进QDs-524、QDs-598和QDs-618的PL峰位红移, (c)在暗室中放置不同时间经圆偏振光照处理和未处理的QDs-618的PL谱, (d)QDs-618在暗室中PL谱峰位随时间的变化

Fig. 2 (a) Experimental configuration of CPL and UnPL irradiation on the QDs; (b) PL spectra of QDs-524, QDs-598 and QDs-618 before and after CPL illumination; (c) PL spectra of QDs-618 with different time of duration in dark after CPL illumination; (d) Peak position change of PL spectra of QDs-618 with different time of duration in dark after CPL illumination

图3 圆偏振光处理后在暗室中放置7 d的QDs-618量子点的XRD图谱(a)和TEM照片(b), 插图是该量子点的HRTEM照片; 非偏振光处理后在暗室中放置7 d的QDs-618量子点的XRD图谱(c)和TEM照片(d), 插图是该量子点的HRTEM照片

Fig. 3 XRD pattern (a) and TEM image (b) of CdTe QDs-618 after CPL irradiation with inset displaying HRTEM image of the sample; XRD pattern (c) and TEM image (d) of CdTe QDs-618 after UnPL irradiation with inset displaying HRTEM image of the sample

图4 (a) 圆偏振光处理和非偏振光处理后的QDs-618量子点的EDS能谱; (b) 圆偏振光照和非偏振光照之下CdTe量子点及其MPA配体的光氧化示意图

Fig. 4 (a) EDS patterns of QDs-618 before and after CPL as well as UnPL irradiation; (b) Schematic diagram of the oxidation process of QDs under CPL and UnPL irradiation

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