The Theoretical Study of the Effect of Number of Substitution of Si and Ge in Bowl C20 on the Thermoelectric Properties

Today there is a heightened interest in the field of theoretical study of thermoelectric properties due to widespread application of thermoelectric materials. In this research, the Seebeck coefficient (S) and Merit Factor (Z) are calculated for C20-nGen and C20-nSin (n=1-5) bowl structures and the most suitable thermoelectric systems are selected. The quantum calculations are done at the level of LSDA/6-31G of Density Functional Theory (DFT). As the temperature increases from 200k to 400k, the seebeck coefficients of these structures decrease for p-type semiconductors and increase for n-type semiconductors. The maximum values of merit factor are achieved for C19Ge1   equal to 1.78at 278k and for C17Si3 equal to 1.03 at 400k. Therefore, the structures of p-type of C19Ge1 and n-type of C17Si3 with more temperature difference are selected as the best thermoelectric systems. The structures of C20-nGen with n=1,2,5 as the both n-type and p-type semiconductors and C20-nSin with n=3 for n-type and also n=1,3 for p-type have Z>1 and are suitable for thermoelectric systems.