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<p>In this work, we employ first-principles calculations based on density functional theory (DFT) and many-body perturbation theory (MBPT) to investigate the structural, electronic, optical, and excitonic properties of a ZnTe/TlSe van der Waals (vdW) heterostructure, along with its constituent ZnTe and TlSe monolayers. Quasiparticle corrections obtained within the GW approximation reveal that the ZnTe and TlSe monolayers have direct and indirect band gaps of 3.02&#xa0;eV and 1.67&#xa0;eV, respectively, with corresponding exciton binding energies of 0.57&#xa0;eV and 0.50&#xa0;eV. The small lattice mismatch of 1.6% between the two monolayers enables the formation of a structurally stable ZnTe/TlSe heterostructure with minimal interface strain. The resulting heterostructure exhibits a direct quasiparticle band gap of 1.20&#xa0;eV and a type-II band alignment, which facilitates efficient charge separation. The inclusion of electron–hole interactions through the Bethe–Salpeter equation (BSE) results in an optical gap of 1.02&#xa0;eV and a reduced exciton binding energy of 0.18&#xa0;eV. The lowest energy exciton in this heterostructure is identified as an interlayer exciton, originating from spatially separated electrons and holes residing in the TlSe and ZnTe layers, respectively. The combination of a small optical gap, moderate exciton binding energy, and multiple bright excitonic resonances across the visible and near-infrared spectral range highlights the ZnTe/TlSe vdW heterostructure as a promising candidate for next-generation photovoltaic and optoelectronic applications.</p>

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Type-II band alignment and interlayer excitons in ZnTe/TlSe van der Waals heterostructure from GW + BSE calculations

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Saeid Ziksari,
  • Hosein Alavi-Rad,
  • Azadeh Kiani-Sarkaleh

摘要

In this work, we employ first-principles calculations based on density functional theory (DFT) and many-body perturbation theory (MBPT) to investigate the structural, electronic, optical, and excitonic properties of a ZnTe/TlSe van der Waals (vdW) heterostructure, along with its constituent ZnTe and TlSe monolayers. Quasiparticle corrections obtained within the GW approximation reveal that the ZnTe and TlSe monolayers have direct and indirect band gaps of 3.02 eV and 1.67 eV, respectively, with corresponding exciton binding energies of 0.57 eV and 0.50 eV. The small lattice mismatch of 1.6% between the two monolayers enables the formation of a structurally stable ZnTe/TlSe heterostructure with minimal interface strain. The resulting heterostructure exhibits a direct quasiparticle band gap of 1.20 eV and a type-II band alignment, which facilitates efficient charge separation. The inclusion of electron–hole interactions through the Bethe–Salpeter equation (BSE) results in an optical gap of 1.02 eV and a reduced exciton binding energy of 0.18 eV. The lowest energy exciton in this heterostructure is identified as an interlayer exciton, originating from spatially separated electrons and holes residing in the TlSe and ZnTe layers, respectively. The combination of a small optical gap, moderate exciton binding energy, and multiple bright excitonic resonances across the visible and near-infrared spectral range highlights the ZnTe/TlSe vdW heterostructure as a promising candidate for next-generation photovoltaic and optoelectronic applications.