High-performance blue light photodetector based on PANI/CdS heterojunction

Abstract

The pursuit of innovative and enhanced p-n junction photo-diodes for application in optical, optoelectronic, and microelectronic devices has become a global research focus. These diodes' fundamental operation hinges on exploiting disparities in band gaps and electronic structures of constituent materials, thereby enabling the rectification of electrical current, permitting it to flow in a single direction. In this study, we present the design and fabrication of a high-performance blue light photodetector, which uses an n-type cadmium sulfide (CdS) thin film and a p-type polyaniline (PANI). The PANI/CdS heterojunction photodetector demonstrates exceptional performance characteristics, achieving a responsivity of approximately 32 mA/W, a detectivity of approximately 4 × 1010 Jones, and a sensitivity of 5.9 × 104 % under blue light illumination at an applied bias of 30 V. Furthermore, this photodetector exhibits a remarkable rectification ratio of 78 and an impressively short response time of 60 μs. The outstanding performance attributes, including rapid response speed and rectification behavior, are attributed to the surface passivation of the CdS material and PANI chain and CdS linkage mediated states, which effectively reduces the dark current. This process enhances the efficient and rapid transport of photo-generated carriers, whereas, the interfacial nature concurrently reducing photocurrent during reverse bias conditions, thus facilitating the observed rectification effect. This research presents a significant advancement in the area of high-performance photodetectors, holding promise for a multitude of applications across optical, optoelectronic, and microelectronic devices.