ZnO量子点的制备及其在白光LED中的应用

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。

Preparation of ZnO Quantum Dots and Their Applications in White LED

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 micros-copy, 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 syn-thesis condition was obtained for the following fabrication of white-LED device. The physical mecha-nism of the device electroluminescence ( EL) was investigated via the measurements of current-volt-age curves and EL spectra. The results show that stable ZnO QDs can be obtained at room tempera-ture when the synthesis condition is set as:concentration ratio of Zn( OAc) 2 to LiOH is 2:1 and re-action time is 3 h. Finally, a p-i-n type LED was constructed by employing p-GaN:Mg wafer and Al2 O3 thin film respectively as hole injection layer and electron blocking layer, and a white EL emis-sion 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 9424 K.