Preparation of High Gain NIR Photodetectors Based on Gradient AgInS2(Se) Thin Films with A W-1 level Responsivity

Abstract

High-performance near-infrared (NIR) thin-film photodetectors hold great promise for biological detection applications. Techniques based on two-dimensional materials, while well-studied, face challenges in achieving large-area detection with a response current that is readable by a multimeter. In this study, we introduce a high‐performance NIR photodetector based on gradient AgInS2(Se) thin films. To fabricate a AgInS2(Se) film with a high selenization rate and minimal stress, we prepared a loosely structured AgInS2 precursor using an ultrasonic spray pyrolysis (USP) method. The photodetectors, based on an AgInS2(Se)/CdS heterojunction, exhibited remarkably high responsivity, achieving 51.58 A W-1 and 0.315 A W-1 at 660 nm and 1050 nm, respectively, under a 2 V reverse bias. Concurrently, they demonstrated exceptionally high external quantum efficiency (EQE) values of 9709.3% and 37.3% at the respective wavelengths. To demonstrate practical applications, we successfully fabricated a large-scale (5×4 cm2, with an active area of 12 cm2) photodetector capable of generating milliamp-level photocurrents under low light conditions. This photodetector was employed for pulse monitoring and assessing the ripeness of kiwifruits, showcasing the potential of this large-scale technology for biological applications.