硫脲修饰法制备高发光性能CdTe量子点

通过巯基水解制备了具有优异荧光特性的碲化镉量子点. 详细研究前驱体镉离子与巯基丙酸(MPA)摩尔比、镉离子浓度等制备条件对大尺寸、高量子产率的亲水性碲化镉量子点光学性能的影响. 在不同的水热生长时间下, 可制备出荧光发射峰位于485-660 nm范围内的不同尺寸的碲化镉水溶性量子点, 荧光发射峰半高宽控制在40-75 nm之间, 量子点的最高量子产率(QY)达到了45%. 并利用硫脲缓慢水解和光解释放自由硫离子, 修饰碲化镉表面, 检测修饰后的量子点在12天内光学性能的变化情况. 通过考察硫脲用量对量子点修饰效果, 发现当n(CdTe)/n(thiourea)=1:4(量子点浓度以镉离子浓度计)时, 硫脲对发射峰为505 nm的碲化镉量子点修饰效果最为理想, 量子点荧光强度加强了5倍, 量子产率达到68.3%.

Luminescent Properties of CdTe Quantum Dots Synthesized by Modifying Thiourea

CdTe quantum dots (QDs) with fantastic optical properties were synthesized in an aqueous solution by thiol ligands. Reaction conditions, such as Cd-to-ligand molar ratio and precursor concentrations, were optimized to well control the QD size and to achieve high quantum yield (QY). High quality water-dispersed CdTe QDs (QY 45%) were obtained in a hydrothermal systemand the QD emission wavelength ranged from 485 to 660 nm detected at room temperature. The full width at half maximum (FWHM) of the emission peaks broadened from 40 to 75 nm. Thiourea was innovatively utilized to chemically modify the surface of CdTe by the hydrolysis and photolysis of thiourea which can release free sulfide ions. The changes in optical properties of these treated QDs were monitored within 12 days. When n(CdTe)/n(thiourea)=1:4 (concentration of QDs according to the cadmium ion concentration), the fluorescence intensity of the CdTe QDs (λex= 505 nm) increased 5 times. The QY increased to 68.3%.