ZnO量子点的制备及其在白光LED中的应用

Preparation of Zn O Quantum Dots and Their Applications in White LED

利用湿化学方法制备合成Zn O量子点,通过改变合成条件(反应时间、反应物浓度、反应温度)对量子点的尺寸及发光性能进行调控。利用透射电子显微镜、吸收光谱、荧光光谱等表征手段,探讨了合成条件对Zn O量子点光学性质的影响,并优化出适用于构建白光LED器件的最佳合成条件。研究结果表明,在反应温度为20℃、反应时间为3 h、前驱体Zn(OAc)_2和Li OH反应浓度比为2∶1时获得的Zn O量子点较为稳定,并在紫外光激发下发出明亮的黄绿色光。在此基础上,以该Zn O量子点为有源层、p-Ga N∶Mg基片为空穴注入层、非晶Al_2O_3薄膜为电子阻挡层构造了p-i-n型异质结LED,在正向注入电流为5 m A时,获得了来自于器件的白光发射,其色坐标为(0.28,0.30),色温为9 424 K。

ZnO quantum dots（ ZnO QDs） were fabricated by wet chemistry method. By varying the synthesis conditions（ reaction time,reagent concentration ratio and reaction temperature）,the size and luminescence properties of ZnO QDs can be effectively controlled. Transmission electron microscopy,UV-Vis absorption spectra and fluorescence spectra were employed to analyze the influence of preparation conditions on optical properties of the synthesized ZnO QDs,and a set of optimized synthesis condition was obtained for the following fabrication of white-LED device. The physical mechanism of the device electroluminescence（ EL） was investigated via the measurements of current-voltage curves and EL spectra. The results show that stable ZnO QDs can be obtained at room temperature when the synthesis condition is set as： concentration ratio of Zn（ OAc）2 to Li OH is 2∶ 1 and reaction time is 3 h. Finally,a p-i-n type LED was constructed by employing p-Ga N∶ Mg wafer and Al2O3 thin film respectively as hole injection layer and electron blocking layer,and a white EL emission under forward injection current of 5 mA was achieved,where the CIE is located at（ 0. 28,0. 30） and the color temperature is calculated to be 9 424 K.