O₂-induced <i>in-situ</i> manipulation of exciton recombination pathways in 2D heterostructures: Submicron, intensity-programmable pixels with rapid write-read-erase capability, as well as 2D O₂-sensor applications

We present a novel oxygen-induced switching between “non-radiative” and “radiative” exciton recombination in a family of 2D heterostructures: monolayer Bi₂Se₃ grown on arbitrary monolayer transition metal dichalcogenides (TMDs), to include TMD alloys. It is believed to be the result of O₂ diffusing/intercalating between between the layers and disrupting the interlayer interaction. The signature photoluminescence (PL) peaks of TMDs are quenched in all as-grown heterostructures, but can be controllably recovered by heating in the presence of oxygen, and then re-quenched by heating in the presence of N₂ or Ar. The intensity PL switching can also be accomplished using a low-power focused laser, while changing the environment from pure nitrogen to air, enabling high control with submicron resolution. This allows for site-programmable, color-selectable, atomically-thin, micron-scale 2D optical “Write-Read-Erase” light-emitting pixels (PLPs) with effective volumes of ~10^-21 m³. The emission intensity can be precisely varied by a factor exceeding 200×, with a wide range of emission energy values in the visible (1.5eV<E_ph<2eV).