Effect of boron substitution on the electronic structure of nanographene and its relevance to the thermoelectric transport properties in nanocarbon ensembles

Density functional calculations are reported on pristine and boron substituted nanographene sheets containing up to 36 rings. The results indicate that increasing the size of the sheet stabilizes high spin states relative to low spin states. Also high spin states are more favorable for non-Kekule structures of nanographene. Boron substitution in the nanographene sheets is found to stabilize low spin ground states over high spin states. The electronic structures of the nanographene sheets are used to help explain recent results on the thermoelectric properties of boron substituted nanographite ensembles.