Photovoltaic Mode Ultraviolet Organic Photodetectors with High On/Off Ratio and Fast Response
| Autor: | Wei E. I. Sha, Wallace C. H. Choy, Xingang Ren, Hugh L. Zhu |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Materials science
Equivalent series resistance business.industry Dynamic range Analytical chemistry Photodetector Response time medicine.disease_cause Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials Active layer Photovoltaics medicine Optoelectronics business Ultrashort pulse Ultraviolet |
| Zdroj: | Advanced Optical Materials. 2:1082-1089 |
| ISSN: | 2195-1071 |
| DOI: | 10.1002/adom.201400227 |
| Popis: | Ultraviolet (UV) organic photodetectors (OPDs) operated in the photovoltaic mode, achieving a very high on/off ratio of 105 and a fast response time of 20 ns (a decay time of 888 ns), are demonstrated in this work. Light-induced tuning of the barrier height at the two interfaces of the carrier-extraction layer and light-induced tuning of series resistance are proposed to obtain the high on/off ratio. Fast response of the device is demonstrated through the ultrafast trap filling process. The high on/off ratio and fast response are simultaneously realized by introducing TiO2 nanocrystals as the electron-extraction layer of OPDs. In addition, the good on/off ratio can be maintained in a wide concentration range of 2,2′-(1,3-phenylene)bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7) from 25% to 3.75% in the N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB):OXD-7 active layer and the corresponding OPDs can also achieve a fast response time simultaneously, good for its practical application. With the optimized device structure, a large detectivity of over 1012 Jones covering the UV-A region (320–400 nm) and a high linear dynamic range of 100 dB are obtained. Additionally, stability of TiO2-based OPDs, which is not well studied but an important parameter for OPDs, is experimentally investigated. |
| Databáze: | OpenAIRE |
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