First-principles Study On Thermoelectric Properties Of "V"-type Graphene Nanoribbons

Due to the global energy crisis emphasis,the thermoelectric properties of thermoelectric materials are more and more intensive.Low dimensional thermoelectric materials are widely studied for their excellent thermoelectric properties,among them,the graphene nanoribbons are studied more.Based on density functional theory and Boltzmann transport equation,the thermoelectric properties of "V"-type graphene nanoribbons have been investigated.Firstly,we calculate the band structure based on the model of the "V"-type graphene nanoribbons,and then,the variation of the Seebeck coefficient,conductivity,and thermoelectric power factor with the various chemical potential of undoped and doped nitrogen graphene nanoribbons at different temperatures are investigated;then,the variation of the Seebeck coefficient,conductivity,and thermoelectric power factor with the various carrier concentration of undoped and doped nitrogen graphene nanoribbons at 300K,500K and 700K are also studied.The results show that,the band structures of undoped and doped "V"-type graphene nanoribbons are similar;with the temperature increasing,the Seebeck coefficient,conductivity,and thermoelectric power factor decrease.The Fermi energy of doped nitrogen "V"-type graphene nanoribbons moves to valence band,the absolute value of Seebeck coefficient increases.The conductivity value of "V"-type graphene nanoribbons can be changed by doping nitrogen atom.Because the thermoelectric power factor is the result of the interaction of Seebeck coefficient and conductivity,discover by computing,thermoelectric power factor of "V"-type graphene nanoribbons with nitrogen atom increases.When the carriers with doped nitrogen graphene nanoribbons are holes,and the holes carrier concentrations are 1021cm-2,thermoelectric power factor reaches 7.69×1011W/K2ms.