Author: P. H. Jariwala, Yashasvi Naik, P. R. Parmar and H. R. Mahida
DOI: -
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In present investigation, first-principle investigation on the structural stability and tunable optoelectronic characteristics of a SnBr₂/CuI van der Waals heterostructure (vdW HTS). The stability of the vdW HTS is also verified by adhesion energy calculations and ab initio molecular dynamics (AIMD) simulations, exhibiting its energetic and thermal stability. Electronic band structure calculations determine SnBr2/CuI vdW HTS to exhibit a direct bandgap near 1.17 eV within the HSE06 functional, in the optimum bandgap regime for solar absorbers. Crucially, the type-II band alignment enables spatial separation of photogenerated holes and electrons, thus inhibiting recombination and favoring carrier transportation across the interface. Charge density difference analysis also validates interfacial charge reconstructions in accordance with efficient carrier exchange. The optical calculations indicate a clear red-shifted absorption edge into the visible regime, along with an increased absorption coefficient over the pure monolayer counterparts, implying enhanced light-harvesting capability. Together, these findings establish the SnBr2/CuI vdW HTS to offer excellent structural stability alongside tunable optoelectronic performance, thus making it an extremely promising next-generation solar and nano-optoelectronic contender.
vdW Heterostructure, Thermophotovoltaic, DFT, Type-II semiconductor
In this work, we have systematically investigated the structural and optoelectronic properties of the SnBr2/CuI van der Waals heterostructure (vdW HTS) using first-principles density functional theory calculations. Our results confirm that the heterostructure is both energetically and thermally stable, as evidenced by the negative adhesion energy and the minimal fluctuations observed in AIMD simulations. The compatibility of lattice constants between SnBr₂ and CuI enables the formation of a stable interface with minimal mismatch, further supporting its structural integrity. From an electronic point of view, SnBr2/CuI vdW HTS has a direct bandgap in the region of about 1.17 eV, within the optimum value for photovoltaic absorbers. Note well that the type-II band alignment for efficient charge transfer over the interface takes place due to the spatial separation of electrons and holes in multiple layers. The band alignment strongly suppresses the recombination losses, thus increasing the probable efficiency in devices by virtue of this heterostructure. Charge density difference calculations and work functions are additional proof to confirm the taking place of the interfacial charge redistribution in support of effective carrier separation. Optical characterizations reveal weak absorption in the visible regime for the pure SnBr2 monolayer, while the SnBr2/CuI heterostructure red-shifts the absorption edge to align the absorption within the visible regime. The above-mentioned features along with the relatively low value of the exciton binding energy indicated by the larger dielectric constant direct towards efficient separation and generation of the photoexcited carrier pairs in the heterostructure. Consequently, the synergistic combination of inherent structural stability, appropriate band alignment, and improved optical response makes the SnBr2/CuI vdW HTS an extremely viable prospect for next-generation photovoltaic and nano-optoelectronic devices. The SnBr2/CuI vdW heterostructure demonstrates type-II band alignment and a direct bandgap, both of which are highly favorable for efficient carrier separation and strong light absorption. These features suggest that the system could be a promising candidate for thermophotovoltaic applications, where optimized bandgaps and charge dynamics are essential for high conversion efficiency.
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P. H. Jariwala, Yashasvi Naik, P. R. Parmar and H. R. Mahida (2025). DFT Study of Type-II SnBr2/CuI vdW Heterostructure: Implications for Thermophotovoltaic Devices. International Journal of Theoretical & Applied Sciences, 17(2): 124–129.
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