1：Experimental Design and Method Selection:

First-principles calculations within the density functional theory (DFT) were performed using the VASP code with projector-augmented wave (PAW) formalism and a generalized gradient approximation (GGA) in the form of Perdew, Burke, and Ernzerhof (PBE) for the exchange-correlation functional. The vdW correction of Grimme’s DFT-D3(BJ) model was involved to describe the interlayer interaction. The dipole correction was also engaged to describe the possible charge redistribution in these heterostructures. Electronic structures were calculated using the screened hybrid HSE06 functional with 25% Hartree-Fock exchange energy.

2：Sample Selection and Data Sources:

The samples considered were isolated InSe and GaTe monolayers and their heterobilayer (HBL) configurations. The lattice constants and electronic band structures were optimized and calculated.

3：List of Experimental Equipment and Materials:

The calculations were performed using the VASP code with PAW formalism, PBE functional, and HSE06 functional for electronic structures. A vacuum space of about 15 ? was applied to avoid interaction between adjacent images.

4：Experimental Procedures and Operational Workflow:

The atomic positions and lattice vectors were fully optimized using the conjugate gradient (CG) scheme without any symmetric restrictions until the maximum force on each atom was less than 0.01 eV/?. The phonon spectra were calculated using a supercell approach within the PHONON code.

5：01 eV/?. The phonon spectra were calculated using a supercell approach within the PHONON code. Data Analysis Methods:

5. Data Analysis Methods: The band edge positions ECBM and EVBM were aligned to the vacuum level. The band offsets of InSe/GaTe HBL were determined from the macroscopic average electricstatic potential. Optical absorption properties were calculated by converting the complex dielectric function to the absorption coefficient.