Ultrafast Electrochemical Synthesis of Defect-Free In2Se3 Flakes for Large-Area Optoelectronics

Because of its thickness-dependent direct bandgap and exceptional optoelectronic properties, indium(III) selenide (In2Se3) has emerged as an important semiconductor for electronics and optoelectronics. However, the scalable synthesis of defect-free In2Se3 flakes remains a significant barrier for its practical applications. Here, a facile electrochemical strategy is presented for the ultrafast delamination of bulk layered In2Se3 crystals in nonaqueous media, resulting in high-yield (83%) production of defect-free In2Se3 flakes with large lateral size (up to 26 mu m). The intercalation of tetrahexylammonium (THA(+)) ions mainly creates stage-3 intercalated compounds in which every three layers of In2Se3 are occupied by one layer of THA molecules. The subsequent exfoliation leads to a majority of trilayer In2Se3 nanosheets. As a proof of concept, solution-processed, large-area (400 mu m x 20 mu m) thin-film photodetectors embedded with the exfoliated In2Se3 flakes reveal ultrafast response time with a rise and decay of 41 and 39 ms, respectively, and efficient responsivity (1 mA W-1). Such performance surpasses most of the state-of-the-art thin-film photodetectors based on transition metal dichalcogenides.