Dielectric environment effects on charged defects in 2D materials

Two-dimensional (2D) materials are the subject of significant ongoing research for technological applications in electronics, optoelectronics and quantum computing. These applications critically depend on the properties of charged defects, which has necessitated the development of computational methods to evaluate energies of charged defects in 2D materials. Such methods overcome the energy divergence from the Coulomb interaction of a charged defect with its periodic images and the compensating background charges. However, these methods do not easily account for the effects of substrates on charged defect properties, which is vital for realistic treatment of 2D materials that cannot be free-standing for most applications. We present a general technique for predicting properties of charged defects in 2D materials with substrates, bringing together accurate prediction techniques for free-standing charged defects with continuum solvation theories. Application of this method to defects in molybdenum disulfide (MoS₂) on various substrates reveals how charge transition levels of these defects evolve with environmental screening effects and will guide the design of defects for 2D devices.