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Utilizing Optical Sensitizers to Realize Ultra-thin Photodetector with High Performance and Thermal Stability

Title
Utilizing Optical Sensitizers to Realize Ultra-thin Photodetector with High Performance and Thermal Stability
Translated Title
열안정성을 갖는 초박막형 고성능 광검출기
Authors
Min Su Jang
DGIST Authors
Jang, Min Su; Lee, Yong Min; Chung, Dae Sung
Advisor(s)
정대성
Co-Advisor(s)
Yong Min Lee
Issue Date
2019
Available Date
2020-02-28
Degree Date
2019-02
Type
Thesis
Abstract
최근 스마트 카, 드론, 머신비전 등 차세대 연구 분야에서 이미지센서에 대한 관심이 늘어남에 따라 이미지 센서의 경량화, 소량화, 고집적화 등 많은 부분들의 기술적 혁신이 요구되고 있다. 본 논문은 구조적 설계를 통해 [6,6]-phenyl-C71-butyric acid methyl es-ter (PCBM) 감광자를 poly(3-hexylthiophene) (P3HT)층과 알루미늄 전극 사이에 고립시켜 고성능 초박막형 광검출기를 제시한다. 기존 광검출기의 경우 PCBM 감광자가 P3HT층 전역에 걸쳐 분포해 있어, 활성층의 두께를 줄이는데 한계가 있다. 반면, 감광자가 고립된 해당 광검출기는 박막의 두께가 얇아져도 percolation pathway가 형성되지 않아 150nm의 매우 얇은 박막에서도 높은 성능을 낼 수 있다. 제시된 초박막형 광검출기는 19V에서 120,700%에 달하는 외부양자효율(EQE)을 보여 고성능 카메라의 픽셀로 충분한 가능성을 보였다. 비교적 낮은 전압인 5V에서도 해당 광검출기는 600%에 달하는 EQE 및 1012에 달하는 광검출능을 보였다. 또한 해당 광검출기의 구조적 안정성에 의해 일반적인 기계장치의 구동온도인 60°C에서 2시간 동안 높은 광검출 성능을 유지하며 열안정성을 보였다.|A thin film planar heterojunction organic photoconductor (PHJ-OPC) is demonstrated by spatially con-fining [6,6]-phenyl-C71-butyric acid methyl ester (PCBM) as a photoconductive sensitizer between hole transporting poly(3-hexylthiophene) (P3HT) layer and cathode. Different from a conventional sensitizer-doped photoconductor, where the sensitizer is distributed throughout the entire active layer, the limited spatial distribution of sensitizer in a PHJ-OPC enables significantly reduced thickness of the active layer without al-lowing the formation of electron percolation pathways. As a result, a photoconductor revealing a peak external quantum efficiency (EQE) of 120,700% at -19V with ultra-thin film of 150 nm is demonstrated, which can be a significant benefit for high resolution image sensor application. The operating voltage can be decreased to -5V while maintaining high detectivity over 1012 Jones and EQE of 600%. Moreover, the morphological robustness of PHJ facilitates remarkable thermal stability with minor change in detectivity for 2 hours of continuous operation at 60°C. This work opens up a possibility of using a thin film PHJ-OPC as a key unit of high-resolution image sensor not only with high photoconversion ability but also with operational stability and low energy consump-tion.
Table Of Contents
Ⅰ. Introduction 1 1.1 Characteristics of organic photoconductor 1 1.2 Photomultiplication-type photoconductor 1 1.3 Planar heterojunction organic photoconductor (PHJ-OPC) 3 ⅠI. Experiment 4 2.1 Materials 4 2.2 Device Preparations 4 2.3 Device Characterization 5 ⅠII. Results and discussions 7 3.1 Structural Design of planar heterojunction OPC 7 3.2 Active layer thickness control 10 3.3 Ultra-thin photodetector 12 3.3.1 Significance of ultra-thin active layer 12 3.3.2 Device performance 13 3.3.3 High thermal stability 15 ⅠV. Conclusions 17 References 18
URI
http://dgist.dcollection.net/common/orgView/200000171515
http://hdl.handle.net/20.500.11750/10724
DOI
10.22685/thesis.200000171515
Degree
MASTER
Department
Energy Science&Engineering
University
DGIST
Related Researcher
  • Author Lee, Yong Min Battery Materials & Systems LAB
  • Research Interests Battery; Electrode; Electrolyte; Separator; Simulation
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Collection:
Department of Emerging Materials ScienceThesesMaster


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