Two-dimensional semiconductors simultaneously having suitable electronic properties and high carrier motilities are highly required in next-generation photoelectronic devices. Herein, we propose a new single-layer semiconductor, CdIn2S4, and investigate its photoelectronic properties utilizing first-principles calculations. Interestingly, we find that single-layer CdIn2S4 holds a quasi-direct moderate bandgap of 1.73 eV. Its valence band maximum and conduction band minimum are located at different atomic regions, which hinders the recombination of generated electrons and holes. Hence, single-layer CdIn2S4 has a suitable electronic structure for optoelectronics. The suitable electronic property also exists under the biaxial strains of −4%, −2%, 2 %, and 4 %, while the electron mobility ranges from ∼3000 to ∼11,000 cm2·V−1·s−1, revealing its potential application in high-speed electronics. In addition, its strong visible absorption and much-reduced exciton binding energy render abundant photogenerated electrons and holes. Summarily, the suitable electronic property, ultrahigh carrier mobility, and abundant visible absorption demonstrate that single-layer CdIn2S4 is a hopeful candidate for high-speed optoelectronics.
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