Theory of the effective Seebeck coefficient for photoexcited 2D materials: the case of graphene

TL;DR

This paper extends the concept of the effective Seebeck coefficient to photoexcited graphene, accounting for photoexcited electron density, providing essential insights for thermoelectric modeling in 2D materials.

Contribution

It introduces a theoretical framework for the effective Seebeck coefficient in photoexcited 2D materials, specifically graphene, considering electron density effects.

Findings

Effective Seebeck coefficient depends on photoexcited electron density and temperature.

Comparison shows the extended coefficient differs from the phenomenological one.

Results are crucial for microscopic thermoelectric theories in graphene.

Abstract

Thermoelectric phenomena in photoexcited graphene have been the topic of several theoretical and experimental studies because of their potential usefulness in optoelectronic applications. However, available theoretical descriptions of the thermoelectric effect in terms of the Seebeck coefficient do not take into account the role of the photoexcited electron density. In this work, we adopt the concept of effective Seebeck coefficient [G.D. Mahan, J. Appl. Phys. 87, 7326 (2000)] and extend it to the case of a photoexcited two-dimensional (2D) electron gas. We calculate the effective Seebeck coefficient for photoexcited graphene, we compare it to the commonly used "phenomenological" Seebeck coefficient, and we show how it depends on the photoexcited electron density and temperature. Our results are necessary inputs for any quantitative microscopic theory of thermoelectric effects in graphene and related 2D materials.