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Surface state controlled high performance self-powered photovoltaic detectors based on individual SnS nanorods with symmetrical electrode structure

Abstract

With decreasing in material size to nanoscale, the surface effect will play a critical role in device performance. Here, individual SnS nanorod-based photodetector shows an excellent sensitivity, selectivity and responsivity modulated controllably by operation bias, illumination intensity and annealing temperature. Surface state governed photovoltaic mechanism is proposed. For the two-terminal devices, two back-to-back diodes can be formed due to the presence of surface barrier. At low operation voltage, the surface barrier dependence of photodetector can show a wideband response in range from ultraviolet (UV) to near infrared with a large photo-to-dark current ratio. At high operation voltage, however, the surface barrier connected with the negative electrode disappears resulted from Fowler–Nordheim tunneling, and accordingly the bulk material dependence of photodetector only shows a narrowband response to the light close to SnS bandgap accompanied with a large darkcurrent. Moreover, the photodetector also shows a negative photoresponse to solar-blind UV light originating from the high absorption coefficient short wavelength light induced the excitation of trapped electrons located in surface space charge region. Based on the tunable principle of nanostructure surface states, self-powered photovoltaic photodetectors with symmetrical structure can successfully be realized by asymmetrically annealing two end electrodes. At zero bias, it can show a relatively large photogenerated voltage and current to weak incident light illumination. The operation bias, illumination intensity and annealing temperature govern photoresponse by the adjustment of surface states, and therefore the nanostructure-based photovoltaic photodetectors with superior performance will have important applications in new-generation optoelectronic devices.

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Publication details

The article was received on 30 Mar 2018, accepted on 04 May 2018 and first published on 10 May 2018


Article type: Paper
DOI: 10.1039/C8TC01503A
Citation: J. Mater. Chem. C, 2018, Accepted Manuscript
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    Surface state controlled high performance self-powered photovoltaic detectors based on individual SnS nanorods with symmetrical electrode structure

    B. Luo, J. Zhao, B. Cheng, G. Chen, T. Ouyang, Y. Pan, B. Li, Y. Xiao and S. Lei, J. Mater. Chem. C, 2018, Accepted Manuscript , DOI: 10.1039/C8TC01503A

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