InSe: A two-dimensional semiconductor with superior flexibility
Two-dimensional indium selenide (InSe) has attracted extensive attention recently due to its record-high charge carrier mobility and photoresponsivity in the fields of electronics and optoelectronics. Nevertheless, the mechanical properties of this material in the ultra-thin regime have not been investigated yet. Here, we present our efforts to determine the Young's modulus of thin InSe (∼1-2 layers to ∼34 layers) flakes experimentally by using a buckling-based methodology. We find that the Young's modulus has a value of 23.1 ± 5.2 GPa, one of the lowest values reported to date for crystalline two-dimensional materials. This superior flexibility can be very attractive for different applications, such as strain engineering and flexible electronics. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement no. 755655, ERC-StG 2017 project 2D-TOPSENSE). EU Graphene Flagship funding (Grant Graphene Core 2, 785219) is acknowledged. RF acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness through a Juan de la Cierva-formación fellowship (2017 FJCI-2017-32919). QHZ acknowledges the grant from the China Scholarship Council (CSC) under no. 201700290035. TW acknowledges support from the National Natural Science Foundation of China: 51672216. ; We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI ; Peer reviewed