Electric field-induced electronic-thermoelectric-optical properties of typical isoelectronic HNC6 monolayers: A theoretical study

Abstract

Using the combined first-principles, tight-binding, and machine-learning interatomic potential approaches, we explore the electric field effects on the electronic, thermoelectric, and optical properties of buckled hexagonal isoelectronic HNC6 monolayers, a member of HAC6 (A = N, P, As) family. These material(s) possess a Dirac cone in their band structure which can be attributed to the same electron count of every site (C/N) and the presence of a weak π bond between carbon and nitrogen atoms. We predict that a transverse electric field can induce a tunable bandgap, the gap is nearly proportional to the electric field strength, suitable for use in the electronics industry. The thermoelectric performance of HNC6 is better than graphene, which can be further improved by the application of an external electric field. The region of the chemical potential for the optimal thermoelectric performance can also be tuned by the electric field. The Wiedemann–Franz ratio deviates from that of ordinary metals and is nearly twice that of graphene and four times that of universal value. For parallel polarization, HNC6 shows pronounced optical response in the infrared and visible region. Plasma frequencies appear in the visible regions which are blue-shifted with electric field strength. The P and As counterpart of HNC6 shows similar electronic, thermoelectric, and optical properties on the application of electric field, with thermoelectric performance even superior to HNC6. These intriguing electronic, thermoelectric, and optical properties in presence of an electric field suggest great potential of HAC6 for novel electronic, energy harvesting, and optoelectronic devices.