Thermodynamics of photoelectric devices

TL;DR

This paper explores the thermodynamics of photodevices like solar cells and photoconductors, revealing how Coulomb interactions influence their efficiency and performance through a minimal two-level model.

Contribution

It introduces a minimal model analyzing the impact of Coulomb interactions on the thermodynamic efficiency of photodevices, highlighting conditions for optimal performance.

Findings

Maximal response and efficiency occur when Coulomb energy matches the transport gap.

Coulomb interaction benefits solar cell performance when below the transport gap.

Photoconductor performance peaks when Coulomb energy equals the transport gap.

Abstract

We study the nonequilibrium steady state thermodynamics of a photodevice which can operate as a solar cell or a photoconductor, depending on the degree of asymmetry of the junction. The thermodynamic efficiency is captured by a single coefficient of performance. Using a minimal model based on a two-level system, we show that when the Coulomb interaction energy matches the transport gap of the junction, the photoconductor displays maximal response, performance, and signal-to-noise ratio, while the same regime is always detrimental for the solar cell. Nevertheless, we find that the Coulomb interaction is beneficial for the solar cell performance if it lies below the transport gap. Our work sheds important light on design principles for thermodynamically efficient photodevices in the presence of Coulomb interactions.