Indium selenide monolayer: strain-enhanced optoelectronic response and dielectric environment-tunable 2D exciton features.

Electronic and optical performances of the β-InSe monolayer (ML) are considerably boosted by tuning the corresponding band energies through lattice in-plane compressive strain engineering. First principles calculations show an indirect-direct gap transition with a large bandgap size. The crossover is due to different responses of the near-gap state energies with respect to strain.