Localized interlayer complexes in heterobilayer transition metal dichalcogenides

Abstract

Here, a prediction is made that, in the presence of donor impurities, the optical properties of type-II transition-metal dichalcogenide (TMD) heterobilayers are dominated by interlayer excitonic complexes bound to the impurity centers. Quantum Monte Carlo calculations reveal the stability of many such complexes, including neutral-donor bound excitons and biexcitons. A theory is developed for radiative decay of such complexes, where the localized nature of these few-carrier states allows recombination even for a finite misalignment between the TMD layers. A multipeak photoluminescence spectrum is predicted, in the energy range where recent experiments have observed broad luminescence peaks. These results provide a new perspective for interpreting the experimental observations, which so far have been attributed only to delocalized interlayer excitons.