Effective Synthesis of Pb₅S₂I₆ Crystals at Low Temperature for Fabrication of a High Performance Photodetector

Sulfoiodide crystals possess promising properties and functionalities that would be used for technical applications in many areas. In this work, rod-like lead sulfoiodide (Pb₅S₂I₆) crystals with a length of about 3 mm have been fabricated via a rapid hydrothermal process at a temperature down to 160 °C for 10 h with the assistance of acid media (hydrochloride acid). Meanwhile, the structure of Pb₅S₂I₆ was characterized, and the optical property of Pb₅S₂I₆ was measured and investigated based on density functional theory calculations. In addition, an individual Pb₅S₂I₆ crystal based photodetector was first constructed on SiO₂/Si substrate, which sensitively responds to stimulated sunlight especially in the visible region with high responsivity (0.567 mA W^–1), high detectivity (2.69 × 10⁹ Jones), and high photoswitching ratio (up to 650). And also, the device presents a short rise/decay time of less than 0.2 s and low noise equivalent power (4.08 × 10^–13 W Hz^–1/2).