Exciton-polaron thermal radiation in two-dimensional semiconductors

In doped semiconductors such as monolayer transitionmetal dichalcogenides (TMDs), the optical properties are predominantly determined by exciton polarons, which are coherent superpositions of excitons and electron-hole excitation pairs in the Fermi sea. Here, we theoretically study the effect of exciton polarons on thermal radiation in doped two-dimensional semiconductors. By deriving an emissivity formula in terms of the dielectric function and the thickness of two-dimensional semiconductors, we show that the emissivity spectrum exhibits a narrow peak at the energy of an exciton polaron. In addition, we find that carrier doping results in an asymmetric emissivity spectrum and a redshift of the peak position, whereas increasing temperature reduces the emissivity peak height. The theoretical framework developed in this study provides a solid foundation for understanding exciton-polaron thermal radiation and opens what we believe to be new possibilities for energy harvesting and similar technologies, are reserved.