Fabrication and Simulation of Quantum Dot Light-emitting Devices

： 为研究量子点发光器件结构与性能的关系，制 备 了 以 ＣｄＳｅ／ＺｎＳ量子点作为发光 层、ｐｏｌｙ－ＴＰＤ作为空穴传输层，Ａｌｑ３ 作为电子传输层的量子点发光二极管，对器件结构及性能参 数进行了表征，结果显示器件具有开启电压低、色纯度高等特点。结合测试数据，对量子点发光二 极管进行了器件结构建模，利用隧穿模型及空间电荷限制电流模型对实验结果进行了分析，研究了 器件中载流子的注入与传输机理。器件测试与仿真结果表明：各功能层厚度会影响载流子在量子 点层的注入平衡，同时器件中载流子的注入与传输存在一转变电压，当外加电压低于转变电压时， 器件中载流子的注入主要符合隧穿模型；当外加电压高于转变电压时，器件中载流子的注入主要符 合空间电荷限制电流模型。研究结果验证了器件结构建模的合理性，可以利用仿真的方法进行器 件结构优化并确定相关参数，这对器件性能的提高具有指导意义。

In order to study the structural performance relationship of quantum dot light emitting devices. Quantum dot light emitting diodes (QLEDs) were fabricated in this paper using CdSe/ZnS quantum dot as the light-emitting layer (EL), poly-TPD as the hole transport layer (HTL), Alq3 as the electron transport layer (ETL). Experiment results show that the QLEDs fabricated have a low turn on voltage and high color purity. The structure and the performance parameters of the device were measured and the results showed that the QLEDs fabricated had a low turn on voltage and high color purity. According to the measured thickness of HTL, EL and ETL, the tunneling model as well as the space charge limited current model (SCLC) were put into use to analyze the experimental results. The carrier injection and transport mechanism were studied through the models. The simulation results showed that the thickness of each film would influence the injection and transportation of carriers inside the QLED. In the meanwhile, we also noticed from the simulation results that there was a transition voltage, when the applied voltage was lower than the transition voltage, the carrier injection inside the QLED was mainly confirmed with the tunneling model; when the applied voltage was higher than the transition voltage, the carrier transportation inside the QLED was mainly confirmed with the SCLC model. The rationality of the models was proved through the experiment results which can be helpful to optimize the thickness of every film as well as to improve device performance.