In2Si2S3X3 (X = S, Se, Te) Janus monolayers: from magnetic element-free spin-Hall transistor to sustainable energy generation†
Abstract
Conventional spintronics uses ferromagnets for spin generation and detection; however, recent experiments have demonstrated highly efficient ferromagnet-free spin-Hall transistors. In this work, we propose a novel multiatomic direct band gap Janus In2Si2S3Te3 monolayer as a channel semiconductor that exhibits a finite spin-Hall conductivity with high charge carrier mobility of 2772 cm2 V−1 s−1 at room temperature. In this model device, a pure spin current can be generated from the charge current using the spin-Hall effect whereas the inverse spin-Hall effect can be used to generate a Hall voltage. Further, this monolayer is predicted to possess a large out-of-plane piezoelectric coefficient of 160 pm V−1 originating from crystal asymmetry and low elastic stiffness. A three-fold enhancement in solar to hydrogen efficiency is obtained for the Janus In2Si2S3Se3 monolayer (∼7.32%) compared to its pristine In2Si2S6 monolayer (∼2.44%). Moreover, this work provides detailed theoretical insights into the emergent electronic and piezoelectric properties of multi-atomic In2Si2S3X3 (X = S, Se, Te) monolayers. Experimental synthesis of multi-atomic CuInP2S6 nanosheets paves the way for the exploration of the proposed semiconductors in spintronics, piezotronics, and water splitting.