高效、稳定多色碳量子点发光材料的可控制备及LED关键问题研究

The current high-performance QD-LED generally use cadmium-group based QD as emitting layer, which does not meet the environmental-friendly requirements. Compared with other low toxicity non-cadmium QDs, carbon dots are non-toxic and excellent luminescent materials for the device fabrication. However, the emission performance of the current carbon dots depend on the excitation wavelength, it is difficult to obtain a pure single color emission for an efficient monochromatic LED. The purpose of this project is to study the instinct structure and luminescent mechanism of carbon dots, and to reveal the material chemistry and physical factors, which affect the radiation mechanism and energy level of carbon dots, and to establish the mechanism of the growth kinetics. Based on the transient fluorescence dynamics, the effects of different surface treatment methods on the carrier transition process and the Auger effect in the films are investigated. The properties of carrier transportation in the carbon dot film were studied. The carrier transport mode and the factors influencing the carrier injection or energy transfer in the LED are analyzed. After the relationship between the structural parameters or layer interface and carrier transport properties are investigated, we confirm the mathematical model of the current versus the bias voltage and the impact on the performance of the device. This project aims to propose a method for the fabrication of highly efficient monochromatic carbon dot LED.

现有高效量子点LED一般采用镉族量子点为发光材料，不符合“绿色”环保要求。与其它低毒无镉量子点比较，碳量子点无毒，是制备无镉量子点LED的优秀发光材料。但是，现有碳量子点的发光特性依赖于激发光波长，难以获得颜色稳定的纯色发光和高效的准单色LED。本项目拟研究碳量子点内在结构与发光机制，揭示影响辐射跃迁和能级结构的材料化学与物理学因素，建立高效、稳定的纯色碳量子点的生长动力学模型和尺寸调控能级的机制；开展碳量子点薄膜的瞬态荧光动力学研究，揭示不同表面处理方法对薄膜中载流子辐射跃迁过程和俄歇效应的影响规律；研究碳量子点薄膜中载流子的迁移特性，分析LED中载流子的输运方式和影响载流子注入或能量转移的因素；研究器件结构参数、界面调控与载流子输运特性的关系，确定电流随偏置电压变化的数学模型和对器件性能的影响规律。通过项目研究，为研制高效稳定、多色无毒量子点LED提供具有实际应用意义的研究思路和方法。

高效量子点LED一般采用镉族量子点为发光材料，不符合“绿色”环保要求。与其它低毒无镉量子点比较，碳量子点无毒，是制备无镉量子点LED的优秀发光材料。本项目主要开展如下研究内容：一是通过调节准单色碳量子点的反应参数、组分比例和表面钝化方法，研究不同尺寸、组分比例准单色碳量子点的光学特性，揭示尺寸、表面态、结晶性及产物中的有机杂质对准单色碳量子点光学特性的影响规律，揭示影响辐射跃迁效率和能级结构的材料化学与材料物理学因素，建立高效、准单色碳量子点的生长动力学模型与调控机制；二是分析化学组分、反应动力学参数等对碳量子点薄膜结构的影响，揭示量子点尺寸调控与薄膜生长物理机制的关系，实现准单色碳量子点薄膜的可控制备，阐明不同表面处理方法对薄膜中载流子辐射跃迁过程和俄歇效应的影响规律；三是研究准单色碳量子点LED 中载流子的输运方式，分析影响载流子注入或能量转移的因素，制备高效准单色碳量子点LED，制备高效准单色碳量子点LED。主要成果有：（1）采用三种方法制备出三种特性的碳量子点材料，获得了激发波长依赖和激发波长不依赖的碳量子点发光材料；（2）确定碳量子点胶体量子点多种辐射跃迁机制，实现碳量子点薄膜厚度、浓度、溶剂调制发光颜色，制备出碳量子点显示薄膜器件；（3）制备出多种结构的碳量子点荧光型彩色准单色发光器件，巧妙利用碳量子点与聚合物之间的无吸收特性，实现颜色稳定的白光器件；（4）发表SCI检索的学术论文39篇，全部影响因子大于3.0的36篇，其中影响因子大于10.0的21篇；（5）获得授权发明专利5项；（6）培养博士研究生4人，硕士研究生4人。