Ionization energies and excited state lifetime of charged defects in Two-dimensional Materials

Defects in 2D materials such as ultrathin h-BN have been found to be promising candidates for single-photon emitters and quantum bits. However, first-principles prediction of accurate defect properties in 2D materials remains challenging, mainly because of the highly anisotropic
dielectric screening and strong many body interactions in 2D materials. In our previous work[1], we solved the numerical convergence issues for defect charge transition levels in 2D materials at both DFT and many body perturbation theory (MBPT) levels; in this talk we will compare different levels of theory and propose the fundamental principles to obtain reliable ionization energies of charged defects in 2D materials. Next, we will show preliminary results of radiative exciton recombination lifetime based on MBPT and phonon-assisted non-radiative recombination lifetime of defects in 2D materials. We compared different recombination processes between defect-defect and defect-band edge states for complex defects in monolayer BN. With our methods, we will design promising quantum defects that have deep defect levels, weak electron-phonon coupling and long excited state lifetime. [1] F. Wu et al, Phys. Rev. Mater. 1, 071001(R), (2017)