Exotic Thermoelectric Properties of Coronene-Cyclobutadienoid Graphene Nanoribbons

Thermoelectric materials traditionally incorporate heavy metals to achieve low lattice thermal conductivity. However, elements such as Te, Bi, and Pb are costly and pose environmental hazards. In this study, we introduce a novel design strategy for thermoelectric materials, focusing on room-temperature, light-element, and high-ZT materials such as coronene-cyclobutadienoid graphene nanoribbons (cor₄GNRs). This material demonstrates a ZT value exceeding 2.1, attributed to its exceptionally low phonon thermal conductivity resulting from its unique edge structure. Importantly, because its electrical conductance and Seebeck coefficient are nearly unaffected by the edge structure, they remain relatively high. This distinct behavior in phonon and electronic transport properties leads to a remarkably high ZT value. Additionally, we discover that applying strain can significantly reduce phonon thermal conductivity, potentially increasing the ZT value to over 3.0. Our findings provide innovative insights for the design and application of advanced thermoelectric materials.