The Molecular Photo-Cell: Quantum Transport and Energy Conversion at Strong Non-Equilibrium

TL;DR

This paper models a molecular photovoltaic cell under strong non-equilibrium conditions using quantum master equations, revealing how decoherence enhances efficiency by facilitating electron relaxation.

Contribution

It introduces a comprehensive quantum approach to analyze energy conversion in molecular photovoltaic cells considering both coherent and incoherent processes.

Findings

Decoherence improves photovoltaic efficiency by accelerating electron relaxation.

Coherent interference effects influence the energy conversion performance.

The method applies broadly to nanoscale systems at non-equilibrium.

Abstract

Non-equilibrium transport properties and energy conversion performance of a molecular photo-voltaic cell are analyzed using the Lindblad master equation within the open quantum systems approach. The method allows us to calculate the dynamics of a system driven by several non-equilibrium sources (a situation we call "strong non-equilibrium"), which is the natural operating condition of photovoltaic cells. We include both coherent and incoherent processes and treat electrons, photon, and phonons on an equal footing. We find that decoherence plays a crucial role in determining both the overall efficiency of the photovoltaic conversion and the optimal energy configuration of the system. Specifically, decoherence leads to better performance, due to a faster relaxation of the excited electrons to the electrodes. We also examine the effect of coherent interference on the efficiency. The approach we propose in this letter is suitable for studying transport and energy conversion in other nanoscale systems at non-equilibrium, where both coherent and incoherent processes take place.