Photodetector can convert optical signals into electrical signals, therefore they are widely used in imaging, remote sensing, spectroscopy, and other fields. Traditional photoconductive photodetector is usually based on a single type semiconductor materials. Such photodetector has many  advantages such as simple structure, low cost. However, it  also has big dark current, low detection sensitivity. By contrast, the photovoltaic detector which is based on semiconductor heterojunction or metal semiconductor schottky junction has the smaller dark current, higher sensitivity and don't need a additional power to drive.

The professor Ming-Qiang Zhu in Wuhan National Laboratory For Optoelectronics laboratory have synthesized the n-type semiconductor cadmium sulfide microwire by bismuth powder catalyzed thermal evaporation. Combining with the commonly used P type semiconductor polymer P3HT, a self powered photodetector based on PN heterojunction have been fabricated. The device can detect ultraviolet to the near infrared spectrum under the zero bias and has a short response time (< 0.2 s). In addition, thanks to the good crystallinity and asymmetric center structure of the CdS microwire,  the UV/visible detectivity of this device can be enhanced by applying suitable tensile strains according to the theory of piezoelectric-optoelectronics. Therefore, the device is expected to be applied to practical photoelectric detection and pressure detection fields.

On February 20, 2017, the results of this study “Piezo - phototronic effect modulated self - powered UV/visible/near - infrared photodetectors -based on CdS: P3HT microwires” are published in the Nano Energy. This work was supported by the National Natural Science Foundation of China (21174045, 51603078, 51673077, 21474034), the National Basic Research Program of China (Grant No.2013CB922104, 2015CB755602), the Fundamental Research Funds for the Central Universities' (HUST: 2016YXMS029), and Director Fund of WNLO.

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