背电极金属光栅调控有机聚合物光电倍增探测器载流子俘获及光电响应特性

The organic polymer photomultiplicatin photodetectors(OPM-PPDs) have many advantages such as light weight, low cost, extensive materials and flexible，which have drawn extensive research attention. In the OPM-PPDs the trapped electrons(holes) assisted holes(electronic) tunneling injection so as to improve the EQE values of the detector. But the response speed of OPM-PPDs is slow and its collection performance of carrier is poor. Metal grating was introduced as the back electrode of the OPM-PPDs. On the one hand, it can improve the light absorption of the device, and on the other hand, it can control the transmission of carrier and improve the collection rate of carrier, which is a effective way to achieve high performance OPM-PPDs..This project proposes to improve the response speed of the OPM-PPDs by the surface plasmons(SPs), excited by metal grating, to control the transmission performance of the carrier and assist the cathode interface electron captured. In this project, a nanoscale concave and convex pattern in random distribution is embossed by means of anodic alumina template. Using SPs the incident light is absorbed by a large amount at the cathode interface to increase the electron traps near the cathode and capture more electrons. On condition hole tunneling barrier will be narrowed and injection efficiency will be enhanced, which make the external quantum efficiency of OPM-PPDs greatly improved.

基于聚合物材料的有机光电探测器具有质量轻、成本低、取材广泛、柔性可弯曲等诸多优点，近年来受到了研究者们的广泛关注。它利用电子（空穴）陷阱辅助空穴（电子）形成隧穿效应提高探测器的EQE值。但是目前有机聚合物光电倍增探测器的响应速度比较慢，其对载流子的收集性能较差。以金属光栅作为有机聚合物光电倍增探测器的背电极，不仅可以提高器件的光吸收，还可以调控载流子的传输，提高载流子的收集率，是实现高性能光电倍增探测器的有效途径。.本项目提出通过金属光栅激发表面等离激元(SPs)，利用其调控载流子的传输性能，辅助阴极界面电子俘获以提高有机光电倍增探测器的响应速度。拟通过阳极氧化铝模板压印方法在阴极界面处引入随机分布的百纳米级凹凸图案，通过SPs使入射光在此处被大量吸收，从而增多阴极附近电子陷阱,使其俘获更多的电子数，达到窄化空穴隧穿能垒和提高空穴注入效率的目的，使外量子效率获得大幅度提高。

有机聚合物材料具有低成本、可调带宽、可溶液旋涂、环境友好、柔性等优点，已经成为制备低成本、高性能光电探测器的不二之选。不同于传统的无机雪崩二极管倍增管，倍增型有机光电探测器可利用陷阱辅助的载流子隧穿效应获得倍增效应，实现器件的外量子效率大于100 %。并表现出高的灵敏度，在这种情况下，不仅使倍增型有机光电探测避免使用额外复杂放大器，更降低了器件成本。更重要的是在微型脉搏血氧仪、可穿戴式健康监护仪等电子器件以及成像传感等领域该器件有着非常重要的应用需求。本项目立足于倍增型有机光电探测器的实际应用需求，以低成本聚合物给体材料P3HT及受体材料PCBM作为活性层，充分发挥有机聚合物半导体材料优异的光电性能，获得了给受体质量比为100:1，电子陷阱辅助空穴隧穿注入的倍增型有机光电探测器；之后，在标准器件中引入原子厚的氧化铝界面修饰层，实现正反双向偏压的响应体异质结倍增型有机光电探测器；再进一步尝试将ZnO纳米颗粒与受体PCBM结合作为双电子陷阱，来辅助空穴从外电路的大量注入，使体异质结倍增型有机光电探测器的器件性能得到改善。最后利用结构为MoO3/Ag/MoO3(MAM)的超薄金属银膜代替ITO作为透明阳极，制备了高性能的柔性倍增型有机光电探测器。