Journal
NANO LETTERS
Volume 17, Issue 10, Pages 6391-6396Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b03263
Keywords
Organic semiconductors; graphene; heterostructure; phototransistors; two-dimensional
Categories
Funding
- National Natural Science Foundation of China [61325020, 61521001, 61106079, 61575153]
- National Key Basic Research Program of China [2013CBA01604, 2015CB351900]
- Jiangsu Shuangchuang program
- Jiangsu Shuangchuang Team Program
- Key Laboratory of Advanced Photonic and Electronic Materials
- Collaborative Innovation Center of Solid-State Lighting and Energy-Saving Electronics
- Fundamental Research Funds for the Central Universities, China
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Interfacing light-sensitive semiconductors with graphene can afford high-gain phototransistors by the multiplication effect of carriers in the semiconductor layer. So far, most devices consist of one semiconductor light absorbing layer, where the lack of internal built-in field can strongly reduce the quantum efficiency and bandwidth. Here, we demonstrate a much improved graphene phototransistor performances using an epitaxial organic heterostructure composed of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and pentacene as the light-absorbing layer. Compared with single light-absorbing material, the responsivity and response time can be simultaneously improved by 1 and 2 orders of magnitude over a broad band of 400-700 nm, under otherwise the same experimental conditions. As a result, the external quantum efficiency increases by over 800 times: Furthermore, the response time of the heterostructured phototransistor is highly gate-tunable down to sub-30 mu s, which is among the fastest in the sensitized graphene phototransistors interfacing with electrically passive light-absorbing semiconductors. We show that the improvement is dominated by the efficient electron hole pair dissociation due to interfacial built-in field rather than bulk absorption. The structure demonstrated here can be extended to many other organic and inorganic semiconductors, which opens new possibilities for high-performance graphene-based optoelectronics.
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