基于叠层有机发光二极管的高效有机上转换器件的研究

As organic upconversion devices have advantages of flexible, low-cost, easy to large area and transparent, they will be widely used in applications of near infrared optical detection and image. But the conversion efficiency of the organic upconversion devices is still relatively low, which greatly affects their practical applications. In this project, we will use tandem organic light emitting diode to solve this problem. Firstly, we will design and fabricate both organic photodetectors and tandem organic light emitting diodes with high external quantum efficiency, which will be used to build high conversion efficiency organic upconversion devices in next step. The working mechanism of the prepared devices will be well studied in the follow aspects. The influence of the energy level of the connect layer to the charge transfer from photodection unit to the light emitting unit, the influence of the position of the light absorbing layer to the infrared light absorption in photodection unit and the influence of the position of the two emitting layers in light emitting unit to the light output coupling efficiency. These studies will help us to identify the interaction in optical and electrical between photodetection unit and the light emitting unit and find the main factors affecting the conversion efficiency. Futhermore, we will select suitable material to optimize the structure of the upconversion devices. And devices with high conversion efficiency and contrast will be realized finally.

有机上转换器件具有柔性、低成本加工、易于实现大面积和透明等诸多优点，在近红外光信号检测和成像等领域有广泛的应用前景。但目前仍存在转化效率比较低的问题，极大影响了它的实际应用。本项目拟利用叠层有机发光二极管作为发光单元来解决器件转化效率低的问题。我们将从高效近红外有机光电探测器和高效叠层有机发光二极管的制备入手开展研究，通过连接层制备高效上转换器件，同时开展器件的工作机理研究。通过探讨连接层能级位置对探测器单元向发光单元电荷传递的影响、光电探测单元吸光层位置对红外光吸收的影响以及叠层发光器件两个发光层位置对器件输出耦合效率的影响，明确光电探测单元和发光单元之间在光学和电学的相互关联性，找出影响转化效率的主要因素，筛选出合适的材料来优化器件的结构，最终实现出具有高转化效率和高对比度的有机上转换器件。

有机上转换器件具有柔性、低成本加工、易于实现大面积和透明等诸多优点，在近红外光检测和成像等领域有广泛的应用前景。但目前仍存在转化效率比较低的问题，极大影响了它的实际应用。本项目利用叠层有机发光二极管作为发光单元来解决器件转化效率低的问题。本项目首先通过降低高效近红外有机光电探测器暗态电流密度入手开展研究，进一步通过如下手段提高发光二极管性能：1、合理排列发光层降低驱动电压和减小效率滚降；2、有效约束电荷载流子的输运平衡；3、有机异质结电荷产生层增强高效平衡电荷注入；4、电荷和激子限制结构实现了激子的高效利用；5、有机异质结电荷作为注入与产生层提高叠层器件效率。之后利用叠层结构制备有机上转换器件，同时开展了器件工作机理的研究。通过探讨连接层能级位置对探测器单元向发光单元电荷传递的影响、光电探测单元吸光层位置对红外光吸收的影响以及叠层发光器件两个发光层位置对器件输出耦合效率的影响，明确光电探测单元和发光单元之间在光学和电学的相互关联性，找出影响转化效率的主要因素，筛选出合适的材料来优化器件的结构，最终实现具有高达29%光光转化效率的有机上转换器件。进一步，我们发现其成像效果优于商用近红外转化卡。