新穎具記憶能力之有機光電晶體之物理機制探討、感測能力提升、新結構發展以及在軟性光感測陣列之應用

Abstract

本計劃將以三年時間，深入研究有機光電晶體的原理，同時將結合有機光電 晶體和有機光二極體的感應原理，提出新型的有機光感應元件。本計劃將使用並 五苯環有機薄膜電晶體(OTFT)的製程架構，在第一年的研究中，將延伸本研究 群的先期研究，也就是我們已經發現利用電場調控可以使OPT具有很大的光靈敏 度(photo responsivity)，但是相關此效應的物理機制還需要更深入的分析與探討， 同時，從目前的研究成果看到，OPT的光靈敏度主要來自於光產生的電子被缺陷 捕捉，造成元件臨界電壓漂移，從而在固定閘極偏壓下，元件的光電流大幅上升。 然而，此缺陷捕捉效應具有很長的反應時間，這限制了OPT在快速光感測陣列中 的應用。因此本團隊將在第一年研究中，設計實驗深入探討OPT光感測的機制； 第二年開始進行製作本團隊提出的新穎元件結構，來大幅增加OPT的光感測速 度，也就是將在OTFT結構中加入donor-like和acceptor-like materials”異質介面”來 有效且快速的拆解照光產生的激子(exciton)，預期可以提出快速且靈敏的有機光 電晶體，同時，讓OTFT和OPT可以在單一製程上完成，大幅提升此技術的價值。 第三年的研究，將把此新穎結構延伸到結合有機半導體和無機非晶金屬氧化物材 料，形成hybrid phototransistor，預期利用無機非晶金屬氧化物的高電子遷移率， 可以更進一步提升元件反應速度，第三年研究也將結合OPT和OLED形成新穎靜 態存取記憶體(SRAM)。

In this 3-years project, we investigate the mechanism of organic phototransistor and propose a novel device structure to form a fast-response sensitive organic phorotransistor (OPT). The novel structure combines the merits of organic photo diode and organic thin-film transistor. It can be fabricated together with OTFT and provide fast response by effectively separating excitons into electrons and holes. In the first year, we design a series of experiment to investigate the mechanism of OPTs. We fabricate pentacene-based organic thin-film transistors (OTFTs) with gate dielectric treated by various kinds of polymer materials. The polymer materials are used to improve pentacene growth and to serve as electron trapping layer under illumination. Then, the photoresponsivity, photo-induced threshold voltage shift, and bias-stress effect of OTFTs with various trapping layers will be analyzed under the irradiation of light with different wavelength and intensity. In the second year, a novel OPT with enhanced trapping layer formed by an acceptor-like material will be fabricated and characterized. With the interface between the donor-like active layer and the acceptor-like trapping layer, light-induced excitons will be effectively separated into electrons and holes. It is proposed that the novel structure can enhance photoresponsivity and, more importantly, enhance the photo response speed. The sensing and recovering behavior will be characterized and the frequency response of the novel OPT will be measured. In the third year, we plan to do two things. 1. Extend the novel OPT into a hybrid OPT that utilize amorphous metal oxide as the trapping layer to contact with organic donor-like active layer. The high electron mobility of amorphous metal oxide material may further enhance the response speed. 2. Integrate the novel OPT and OLED together to form a novel SRAM. In this project, we propose and verify a novel OPT and deeply investigate the mechanism of OPT. It is believed that the output of this project facilitate the development of organic electronics including flexible display with touch panel, flexible scanner, large-area low-cost camera, and many kinds of organic sensors.