We present theoretical results for the radiative rates and doping-dependent photoluminescence spectrum of interlayer excitonic complexes localized by donor impurities in ${\mathrm{MoSe}}_2/{\mathrm{WSe}}_2$ twisted heterobilayers, supported by quantum Monte Carlo calculations of binding energies and wave-function overlap integrals. For closely aligned layers, radiative decay is made possible by the momentum spread of the localized complexes' wave functions, resulting in radiative rates of a few $\mu {\mathrm{s}}^{-1}$. For strongly misaligned layers, the short-range interaction between the carriers and impurity provides a finite radiative rate with a strong asymptotic twist angle dependence $\propto {\theta }^{-8}$. Finally, phonon-assisted recombination is considered, with emission of optical phonons in both layers resulting in additional, weaker emission lines, redshifted by the phonon energy.

• Received 16 February 2018

DOI:https://doi.org/10.1103/PhysRevB.97.195452