多孔石墨烯纳米带各向异性和超低热导的理论研究

Theoretical study of anisotropy and ultra-low thermal conductance of porous graphene nanoribbons

利用非平衡格林函数方法研究了多孔石墨烯纳米带的热输运性质.结果表明,由于纳米孔洞的存在,多孔石墨烯纳米带的热导远低于石墨烯纳米带的热导.室温下,锯齿型多孔石墨烯纳米带的热导仅为相同尺寸锯齿型石墨烯纳米带热导的12%.这是由于多孔石墨烯纳米带中的纳米孔洞导致的声子局域化引起的.另外,多孔石墨烯纳米带的热导具有显著的各向异性特征.相同尺寸下,扶手椅型多孔石墨烯纳米带的热导是锯齿型多孔石墨烯纳米带的2倍左右.这是因为锯齿型方向上声子局域比扶手椅型方向上更加强烈,甚至部分频率的声子被完全局域导致的.

The thermal transport properties of porous graphene nanoribbons are studied by the non-equilibrium Green’s function method.The results show that owing to the existence of nano-pores,the thermal conductance of porous graphene nanoribbons is much lower than that of graphene nanoribbons.At room temperature,the thermal conductance of zigzag porous graphene nanoribbons is only 12%of that of zigzag graphene nanoribbons of the same size.This is due to the phonon localization caused by the nano-pores in the porous graphene nanoribbons.In addition,the thermal conductance of porous graphene nanoribbons has remarkable anisotropy.With the same size,the thermal conductance of armchair porous graphene nanoribbons is about twice higher than that of zigzag porous graphene nanoribbons.This is because the phonon locality in the zigzag direction is stronger than that in the armchair direction,and even part of the frequency phonons are completely localized.