Ab-initio modeling of electron transport in polycrystalline materials using the space-dependent Boltzmann transport equation

Electron transport in polycrystalline materials involves concurrent phonon and grain boundary (GB) scattering. The conventional—Mayadas-Shatzkes (MS) model—treats GBs as uniform, momentum-independent barriers using a delta potential (among other simplifications) and requires phenomenological parameters. Here, we develop an accurate, first-principles approach based on space-dependent Boltzmann transport equation (SD-BTE) and Poisson equation (PE). This method enables treatment of both phonon and GB scattering by self-consistently solving for the local electric field, electron distribution, and current density across the interface. Applying this approach to mirror twin boundaries (MTBs) in 2D MoS₂, we find that the local mobility exhibits strong spatial modulation, and the resulting field profiles exhibit sharp features localized at interfaces, crucial for maintaining constant current across scattering boundaries. Our results establish a rigorous, first-principles approach for connecting atomic-scale GB structure with carrier transport, providing a foundation for realistic modeling of polycrystalline materials.