低压快响应高增益有机光电探测器的分子特性及其器件关联性研究

To detect weak light or single photon, photodetectors are required to have a high gain for an enough photosensitivity. Photoconductivity gain is traditionally based on the time of carriers staying in a device longer than the carriers striding over it. However, in the traditional mode, the devices can't simultaneously realize high-gain, fast-response-time and low-working-voltage. In our previous research work, we found a photodiode had the simultaneous performances. In this project, the mechanism of the novel high-gain will be clearly disclosed from the cooperated researches of organic molecules and devices. We will select proper organic small molecules as a trap, and synthesize new polymers containing the trap molecules. The basic mode of the gain in this work and the connections between the molecules of organic polymers and the gain of devices will be investigated in detail. Then, we will try to obtain novel near-infrared(NIR) organic photodetectors by preparing new polymers and organic-inorganic hybrid devices. By this project, it will pave a new pathway to realize high performance photodetectors with the high gain in a novel mode, and it will also provide significant references to the design and synthesis of organics and polymers for use in high performance organic photodetectors.

光电探测器需要有很高的增益才能获得足够高的灵敏度以满足对微弱光或单光子探测的要求。传统的光电导增益主要是基于载流子在器件内部停留时间大于其跨越器件的时间，这种器件很难同时兼具高增益、快响应和低电压。我们在前期研究中发现了一种兼具这些高性能的有机二极管。本项目从有机分子角度出发，结合器件研究，揭示这种新型的光电探测器运行机理。本项目将从缺陷态有机小分子的选择、含缺陷态聚合物的合成制备和有机聚合物分子与器件高增益之间的关联性等方面进行详细研究。在此基础上，通过新型聚合物和有机无机杂化等方式研究获得性能全面优越的高增益近红外有机光电探测器。本项目的研究，将为未来光电探测器的研究提供一种全新的增益模式和器件实现途径，并对设计合成新型有机聚合物材料用于获得高性能有机光电探测器的研究提供非常有意义的思路参考。

针对如何避免传统光电导型探测器的增益模式中的高光电增益与较低的噪声电流、工作电压和较快的响应速度难以兼得的瓶颈问题，本项目在前期工作的基础上，通过新型共轭聚合物的合成及其性质的研究，提出了新的策略——利用有机窄带隙共轭聚合物的缺陷态俘获电子以实现光电探测器增益的提升。通过这种策略可以降低器件的暗电流和噪声，提高外量子效率、响应度和比探测率，以使得该类探测器能满足弱光探测、近红外响应等应用要求，拓宽其应用范围。这种策略可进一步应用到多种现有的聚合物/富勒烯共混活性层体系中，且通过光电容积脉搏波描记法测试证实了所制备的有机光电探测器在无创体外检测技术中的潜在应用价值，为实现兼具高增益、高比探测率、低工作电压、低噪声、可快速响应的有机光电探测性能提供了新的设计思路。