First-principles determination of high thermal conductivity of PCF-graphene: A comparison with graphene

Poly-cyclooctatetraene framework (PCF)-graphene, an emerging all-sp² hybridized two-dimensional (2D) carbon allotrope, possesses an intrinsic direct bandgap (0.77 eV) and excellent mechanical properties, indicating great potential in nanoelectronics. Understanding the thermal transport behavior of PCF-graphene is of vital importance for determining the reliability of related devices based on it. In this work, the thermal transport in PCF-graphene is systematically studied using the Boltzmann transport theory combined with first-principles calculations. The results show that the room-temperature thermal conductivity of PCF-graphene with only considering three-phonon scattering is as high as 1587.3 W/m K along the zigzag direction, and decreases by 27.1% (1157.4 W/m K) when including four-phonon scattering, indicating the four-phonon scattering plays a non-negligible role in in thermal transport. Although the thermal conductivity of PCF-graphene is not as large as that in graphene, it still exceeds most common 2D materials and makes it suitable for applications in the thermal management of microelectronics. Analyses of phonon group velocity and phonon scattering rates are conducted to reveal the high thermal conductivity of PCF. Moreover, as the temperature increases to 800 K, the reduction of thermal conductivity is close to 50% after including four-phonon scattering. The analysis of phonon group velocity and phonon scattering rates are conducted to reveal the underlying mechanism. Our results provide insights for constructing high-thermal-conductivity materials based on 2D carbon allotropes.