Low‐Temperature Growth of High‐Quality Ag₂HgS₂ Crystals for Setup of Weak‐Light UV–Visible–NIR Photodetectors

Abstract Weak‐light photodetection shows considerable potential in both theoretical and technical aspects while it would be a key issue to explore new candidate materials for practical application in view of high reliability and durability of the devices under ambient conditions. In this work, Ag₂HgS₂ single crystal rods (SCRs) with length up to 1.2 cm and width ranging from 10 to 200 µm are successfully fabricated in pure phase via facile solvothermal process at 200 °C for 24 h for the first time. The Ag₂HgS₂ SCRs are technically investigated, and the study reveals that they are in high quality via the determination of their crystal structure, morphology, and optical properties. Density functional theory (DFT) calculations are carried out to explore more reliably details on the band structure of bulk Ag₂HgS₂. Meanwhile, a series of photodetectors based on the individual Ag₂HgS₂ SCRs are fabricated, and they convey sensitive responses to a 0.170 µW cm⁻² weak light and unanimous responses to incident light with different wavelengths from 254 to 980 nm. In addition, the devices show excellent detecting performances without any obvious slump after the Ag₂HgS₂ SCRs exposed in air over 18 months.