An Efficient Descriptor for Rapid Determination of Dipole Moments and Band Alignments of 2D Janus Transition‐Metal Dichalcogenides

Abstract The dipole moment (µ) is a critical parameter in Janus structures, influencing band alignments and carrier transmissions. However, evaluating µ in 2D Janus layers is challenging due to the vast number of structures and the inefficiency of Kelvin probe force microscopy. Using the recently developed 2D Janus transition‐metal dichalcogenides (TMDCs) as a prototype, a descriptor is proposed based on fundamental parameters (atomic number and atomic radii) to investigate the relationship between atomic structures and µ. By constructing 621 structural models, this descriptor is applicable from monolayers to three‐layers. By considering shielding effect of terminal atoms, the performance of the descriptor has been significantly enhanced, resulting in a description accuracy of 94.6% for all TMDC systems. Based on this descriptor, the Anderson's Rule (AR) model can be extended to Janus bilayers in simulating band alignments, resulting in a substantial improvement in accuracy from 20.0% to 90.8%. This development holds crucial importance in screening Janus self‐doping P‐N junctions. The work provides an efficient descriptor based on inherent atomic properties for rapid determining dipole moment and band alignment in 2D Janus TMDCs, accelerating the design of devices with built‐in electronic field structures.