Lateral Photocurrent-Induced High-Performance Self-Powered Photodetector Observed in CIGS Heterojunction

Abstract

With the shortage of energy and the development of technology, self-powered devices are promptly needed and aroused much concern in the world. However, restricted to the working principle, external biases are usually needed to get high longitudinal photocurrent responses for the current prototype devices. Here, the lateral photovoltaic effect (LPE) is first introduced to study the lateral photocurrent (LPC) responses in the Cu(In,Ga)Se2 (CIGS) heterostructure. It is found that the CIGS heterojunction can be developed to both an LPC-based self-powered position-sensitive detector (PSD) and photodetector. This PSD shows ultralarge LPC responses in a wide spectral range with a position sensitivity of up to 4.66 mA/mm (at 532 nm) and can work in different contact distances as large as 10.2 mm with excellent linearities. Moreover, the LPC responses can be considerably improved by modulating the thickness of the indium tin oxides (ITOs) layer, which can be mainly attributed to the ITO thickness-dependent external quantum efficiency of the CIGS devices. For the photodetector, the responsivity reaches up to 0.197 A/W but exhibits a nearly reverse laser power- and contact distance-dependent changing tendency with the position sensitivity due to their different definitions.