The catalyst-free growth of layer-structured CuInSe2/β-In2Se3 microwires for ultrasensitive self-powered photodetectors based on a lateral p-n junction

Herein, layer-structured beta-In2Se3 microwires were obtained via a facile chemical vapour deposition (CVD) method without any catalyst. As a novel kind of building block for constructing photodetectors, this one-dimensional (1D) layer-structured beta-In2Se3 can overcome issues relating to the persistent photoconductance effects of 1D materials and the insufficient optical absorption of two-dimensional (2D) layered materials. Utilizing the high carrier mobility of layered beta-In2Se3, a lateral p-n junction based on CuInSe2/In2Se3 microwire was subsequently assembled via a simple solid-state reaction using these same layers. The lateral p-n junction, with a high rejection ratio of 10(2), exhibits excellent photovoltaic characteristics. In particular, a high on/off ratio of 4 x 10(2) could be achieved under a light intensity of 25.18 mW cm(-2) (405 nm) without any power supply. Moreover, the dark current is 1.5 pA, which is smaller than most previous InxSey-based photodetectors. The responsivity of the device can reach a highest value of 10.52 mA W-1. This value is comparable to those of pristine In2Se3 device at 0.1 V and CuInSe2 device at 0.5 V. Also, the response times are one order of magnitude faster than those of pristine In2Se3 and CuInSe2 devices. This work offers new insight into the rational design of 1D or quasi-1D multilayer semiconductors for use in high-performance, low-cost, and energy-efficient photodetectors.