Tuning the thermoelectric efficiency of a polyaniline sheet using strain engineering

Abstract

Two-dimensional polyaniline monolayers (C3N) have been recently synthesized as indirect semiconductors with high electron mobility. We investigate the electrical and thermal properties of a C3N sheet using a combination of density functional theory and the Green function formalism. Tensile strain along a zigzag direction can drive the transition from an indirect to a direct semiconductor, whereas the sheet transitions from a semiconductor to a metal under compressive strain. The thermoelectric efficiency of an unstrained C3N sheet is higher in p-doping, and its maximum value is obtained when the transport is along the zigzag direction. A reduction in the figure of merit is found upon applying strain, independent of its direction. To overcome this reduction, we show that when the electrical transport and strain are perpendicular to each other, the thermoelectric efficiency of the C3N sheet can be significantly increased, depending on the type of strain (tensile or compression). The results support the potential application of C3N sheets in the thermoelectrics and optoelectronics industries through using strain engineering.