Single-layer and bilayer In2SeO2: Direct bandgap and reduced exciton binding from first-principles calculation

Abstract

Two-dimensional semiconductors having direct bandgaps and weak exciton binding are necessary for highly integrated optoelectronic devices. Herein, single-layer (SL) and bilayer (AA and AB) In2SeO2 are proposed for the first time and studied using first-principles calculations. Both SL and bilayer In2SeO2 are of experimental feasibility for good stability. SL and bilayer AB In2SeO2 show moderate direct bandgaps at the HSE06 level. Their abundant visible-light absorption and weak exciton binding promise the successful generation of separated carriers. The high electron mobility of SL (∼3000 cm2·V−1·s−1) and bilayer AB (∼2600 cm2·V−1·s−1) suggests the possible application in electronics. The effective separation of electrons and holes is further confirmed by the huge discrepancy in carrier mobility and long-lived charge carriers. Summarily, our calculations support that In2SeO2 is a promising candidate in ultrathin optoelectronic devices.