Optoelectronic Properties of a van der Waals WS<sub>2</sub> Monolayer/2D Perovskite Vertical Heterostructure
Qixing Wang, Qi Zhang, Xin Luo, Junyong Wang, Rui Zhu, Qijie Liang, Lei Zhang, Justin Zhou Yong, Calvin Pei Yu Wong, Goki Eda, J. H. Smet, Andrew T. S. Wee
Abstract
Two-dimensional (2D) Ruddlesden–Popper perovskites have been demonstrated to possess great potential for optical and optoelectronic devices. Because they exhibit better ambient stability than three-dimensional (3D) perovskites, they have been considered as potential substitutes for 3D perovskites as light absorbing layers to improve the photoresponsivity of monolayer transition metal dichalcogenide (TMDC)-based photodetectors. Investigation of the optoelectronic properties of TMDC monolayer/2D perovskite vertical heterostructures is however at an early stage. Here, we address the photovoltaic effect and the photodetection performance in tungsten disulfide (WS2) monolayer/2D perovskite (C6H5C2H4NH3)2PbI4 (PEPI) vertical heterostructures. A vertical device geometry with separate graphene contacts to both heterointerface constituents acted as a photovoltaic device and self-driven photodetector. The photovoltaic device exhibited an open circuit voltage of −0.57 V and a short circuit current of 41.6 nA. A photoresponsivity of 0.13 mA/W at the WS2/PEPI heterointerface was achieved, which was signified by a factor of 5 compared to that from the individual WS2 region. The current on/off ratio of the self-driven photodetector was approximately 1500. The photoresponsivity and external quantum efficiency of the self-driven photodetector were estimated to be 24.2 μA/W and 5.7 × 10–5, respectively. This work corroborates that 2D perovskites are promising light absorbing layers in optoelectronic devices with a TMDC-based heterointerface.