Generalized Energy Band Alignment Model for van der Waals Heterostructures with a Charge Spillage Dipole.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Energy band alignment is crucial for van der Waals heterostructures (vdWHs) in advanced electronic and optoelectronic devices.
• Traditional models like Anderson and midgap fail for vdWHs, especially type-III systems, due to limitations in capturing interface physics.

Purpose of the Study:

• To develop a more accurate model for predicting energy band alignment in vdWHs.
• To address the limitations of existing models in describing the unique interface properties of vdWHs.

Main Methods:

• Utilized first-principles calculations (density functional theory - DFT) for approximately 10^3 vdWHs.
• Introduced a generalized linear response (gLR) model incorporating a quantum capacitance term to account for interlayer charge spillage.
• Employed machine learning for feature analysis to identify dominant physical descriptors.

Main Results:

• Demonstrated that traditional models miss a critical dipole from interlayer charge spillage in vdWHs.
• The gLR model accurately reproduces DFT band line-ups (r^2 ~ 0.9) for type-I, -II, and -III vdWHs using only two input parameters.
• Machine learning confirmed the dominance of charge neutrality level offset and isolated-layer bandgaps in the model's accuracy.

Conclusions:

• The gLR model offers mechanistic insight into vdWH band alignment.
• It serves as a fast and accurate surrogate for high-throughput screening of vdWH materials.
• This framework accelerates the design and discovery of novel vdWH-based electronic and optoelectronic devices.