Silicon biphenylene network: A versatile 2D material platform for nanoelectronics with tunable electronic, thermal, and thermoelectric properties

M Alidoosti and R Shayanfar and DN Esfahani and D Vashaee, MATERIALS TODAY ADVANCES, 28, 100610 (2025).

DOI: 10.1016/j.mtadv.2025.100610

The silicon biphenylene network (SBN), a two-dimensional (2D) material analogous to its carbon-based counterpart, the carbon biphenylene network (CBN), exhibits distinct structural, electronic, and thermal properties that differentiate it from other 2D materials. Using first- principles calculations and Boltzmann transport theory, we show that SBN is dynamically, mechanically, and thermodynamically stable, with a unique buckled geometry, featuring three distinct buckling heights and four different bond lengths, that leads to subtle mechanical anisotropy. Strain engineering allows further tuning of both structural and electronic properties, including the appearance of a tilted Dirac cone approximately 150 meV above the Fermi level. SBN exhibits a low lattice thermal conductivity (similar to 8.8-9.2 W/mK at room temperature), considering both particle-like and glass-like components. This behavior is attributed to phonon hybridization and enhanced scattering induced by structural buckling, which remains robust under tensile strain. We also observe a significant, anisotropic deviation from the Wiedemann-Franz law, particularly along the x direction at elevated temperatures. Moreover, all key thermoelectric properties - including thermal conductivity, electrical conductivity, and thermopower - exhibit pronounced anisotropy. As a result, the thermoelectric figure of merit in one direction is more than five times greater than in the orthogonal direction, highlighting SBN's potential for directional heat flow control and anisotropic device applications. These findings position SBN as a tunable and versatile 2D platform for future nanoelectronics, thermoelectrics, and integrated thermal management systems.

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