Thermoelectric properties of pristine and defective α-graphyne nanoribbons with vacancies present in different positions

In the present work, first-principle thermoelectric property investigations of pristine and defective alpha-graphyne nanoribbons (alpha-GYNRs) are conducted. Investigations have also been extended toward variation in temperature affecting the thermoelectric properties. Other objectives of the work presented are to investigate the thermoelectric properties at three temperatures, 300K, 500K, and 700K, of a single vacancy defect in a carbon atom removed from alpha-GYNRs. Pristine alpha-GYNRs is an intrinsic band gap semiconductor since defects occur naturally during synthesis, and the band gap significantly increases due to single vacancies and removal of carbon atoms at different positions. It results in a change of electrical conductivity Seebeck coefficient, and thermal conductivity. For some defective structures, with increasing temperature, the Seebeck coefficient increases compared with that of the pure structure and decreases. Also, the total thermal conductivity increases with increasing temperature. The obtained results show that the figure-of-merit value of defective alpha-GYNRs is much better than pristine alpha-GYNRs. In addition, ZT decreases in different structures by increasing temperature. Among all the considered structures, the Seebeck coefficient values and the ZT of some defective structures reach about 1.18 and 2.5 times that of the pristine structures at room temperature, respectively.