Isomorphous Substitution Synthesis and Photoelectric Properties of Spinel AgInSnS4 Nanosheets

Multinary metal chalcogenides, a remarkable class of materials for designing multifunctionality, possess a broad variety of physical and chemical properties and hold a great promise for a wide range of potential applications. As a typical quaternary I–III–IV–VI4 group semiconductor, spinel AgInSnS4 has only received extremely limited attention probably due to difficulty in synthesis. In this work, for the first time, AgInSnS4 nanocrystals have been successfully fabricated via a simple isomorphous substitution approach using spinel indium sulfide as the parent material. The prepared AgInSnS4 nanosheets perfectly maintain the cubic spinel structure. The optical absorption results show that the obtained spinel AgInSnS4 nanocrystals exhibit strong absorption in the visible-light region and have a direct band gap of about 1.54 eV. The band structure analysis indicates that the AgInSnS4 product should display p-type conduction. Photocurrent measurements reveal that the spin-coated thin film of AgInSnS4 nanosheets can exhibit a broad, sensitive, fast, and stable photoelectric response. The favorable optical and photocurrent properties suggest a significant potential of the prepared spinel AgInSnS4 nanocrystals for applications in photovoltaics and other optoelectronic devices.