Unraveling the four-phonon scattering mechanism in the exceptional thermal conductivity of TTH-carbon

TTH-carbon, a novel two-dimensional all-sp3 carbon allotrope, exhibits excellent stability and high carrier mobility, promising for nanoelectronic applications. To assess its device reliability, we systematically evaluated its thermal transport properties through first-principles calculations combined with the Boltzmann transport equation. Under only three-phonon scattering, TTH-carbon demonstrates ultrahigh in-plane thermal conductivities of 699.5 W m−1 K−1 along the x-direction and 952.6 W m−1 K−1 along the y-direction at room temperature. Phonon mode analysis reveals that ZA and LA modes dominate the heat conduction. Introducing four-phonon scattering substantially reduces these values to 372.6 W m−1 K−1 (a reduction of 53.3%) and 649.3 W m−1 K−1 (a reduction of 68.2%) in the x-direction and y-direction, respectively. This strong reduction is due to strongly enhanced scattering of the dominant acoustic phonons—yet these values still surpass most reported 2D materials. Crucially, four-phonon scattering selectively suppresses the ZA mode along the x-direction, resulting in a substantially increased in-plane thermal anisotropy. This work demonstrates the potential of TTH-carbon for advanced thermal management.