The Role of Width Modulation in Increasing the Efficiency of Thermoelectric Generators

In this paper, the thermoelectric properties of graphene-based structures are assessed by tight-binding method using Landauer-Buttiker formulas. Although a decline in the width of the grapheme nanoribbon can increase the thermoelectric figure of merit, the proper design of the nanostructures is still possible. Based on the results, a periodic alteration in the width of the ribbon, also known as the ribbon width modulation, could enhance the figure of merit twice compared with that of the narrow ribbon. Moreover, for the case with gradual changes in the ribbon width, three-fold enhancement could be achieved in the thermoelectric figure of merit compared to that of narrow ribbons. Such an increment could be assigned to an increase in the bandgap and, thus, the increment in the Seebeck coefficient, the power factor as well as the thermal conductance reduction.