Chargeable photoconductivity in van der Waals heterojunctions of black phosphorus and quasi-two-dimensional electron gas

Abstract

<p>Nowadays, there is a surge of research reports on photovoltaic cells and photodetectors based on van der Waals (vdW) heterojunction. However, there are very few reports on the simultaneous realization of photoelectric conversion and storage in a single device. Herein, a simple method was utilized to successfully prepare a van der Waals heterojunction with a chargeable photoconductivity (CPC) effect between black phosphorus and quasi-two-dimensional electron gas. After a single optical illumination, the device generated photocarriers and stored them for up to 5 days, followed by a bias voltage applied in the dark to release a large photocurrent of 1.0 mA and a current ratio of up to 108 before and after full optical charging. Firstly, experiments showed that the CPC effect critical temperature was approximately 100 K, which is 20 K higher than the highest temperature reported in the literature. Secondly, the CPC effect spectral range of the device increases from 405 nm–808 nm to 405 nm–1064 nm, including even general daylight, indicating that the device’s responsivity and photon collection ability are more prominent. This discovery provides a new direction, to the best of our knowledge, for storage photoconductors and high-efficiency photoelectric storage devices.</p>