The band gap modulation of monolayer Ti₂CO₂ by strain

Ti₂C is the thinnest member in the MXene family with great potential for applications. In the present study, we have investigated the band gap modulation of O-terminated Ti₂C (Ti₂CO₂) monolayer under biaxial or uniaxial strain through first-principles simulation. Our results reveal that monolayer Ti₂CO₂ could undergo an indirect to direct band gap transition under the biaxial strain of ∼4%, and the uniaxial strain of ∼6%. Similarly, the band gap modulation also occurs in monolayer Zr₂CO₂ and Hf₂CO₂ when 10% and 14% biaxial strains are applied, respectively. The detailed reasons for the band gap modulation are also discussed. Our studies have crucial implications for the application of monolayer MXene in opto-electronics and optical devices.