Xinhong Zhao,Yu Tao,Jixiang Dong,Yongchu Fang,Xiaoxian Song,Zaoxue Yan
Wearable, portable, and biocompatible optoelectronic devices made of all-green and abundant materials and fabricated by low-temperature solution method are the key point in the development of next generation of intelligent optoelectronics. However, this is usually limited by the weaknesses of mono-component materials, such as non-adjustable photoresponse region, high carrier recombination rate, high signal-to-noise ratio, as well as the weak mechanical flexibility of bulk films. In this work, the Cs3Cu2I5/ZnO heterostructure flexible photodetectors were constructed by a low-temperature solution method combined with spin-coating technique. The heterostructure combines the low dark current and strong deep ultraviolet absorption of Cs3Cu2I5 quantum dots with the high carrier mobility of ZnO quantum dots as well as the efficient charge separation of the vertical p–n junction, to improve the photodetection performance. The heterostructure shows enhanced light/dark current ratio and ultraviolet-to-visible rejection ratios. Under an illumination of 280 nm light, an optical detectivity as high as 1.26 × 1011 Jones was obtained; the optical responsivity and response time are much better than those of control devices. After 300 times of 180° bending cycles, the photocurrent had no obvious change. The results demonstrate that the Cs3Cu2I5/ZnO heterostructure has great potential in wearable and portable visible-blind ultraviolet optoelectronic devices.
Wei Wang,Yujun Deng,Shuai Sun,Massimiliano Galluzzi,Yang Jiao,Paul K. Chu,Zeren Li,Jia Li,Jianquan Yao
Visible-blind ultraviolet (VBUV) photodetectors are designed for UV detection without responding to visible light, thus having many applications in communications, flame detection, environment monitoring, and astronomy. Herein, an organic device concept based on the bulk heterojunction (BHJ) photodiode is presented for high-performance VBUV photodetection and imaging. The BHJ, comprised of an organic electron donor, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT), and an electron acceptor, indene-C 60 bisadduct (ICBA), shows efficient generation and transport of free charges upon UV irradiation. The organic photodiode (OPD) delivers exceptional VBUV photodetection performance. At a low voltage of −0.5 V, the device exhibits a wide linear dynamic range of 98.15 dB. Furthermore, the OPD can detect ultra-low light intensities down to 0.58 µW cm −2 with a high photoresponsivity of 0.12 A W −1 and specific detectivity of 2.75 × 10 12 Jones. More importantly, by integrating the OPD with a readout integrated circuit, the pixel-array organic VBUV imager is demonstrated to have high-quality imaging capability. The results reveal a novel strategy to design VBUV photodetectors and imagers with balanced performance, cost, area, flexibility, and power consumption.
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