Thermodynamic performance of hot-carrier solar cells: A quantum transport model

TL;DR

This paper models hot-carrier solar cells using quantum transport to analyze how extracting carriers from a nonequilibrium distribution can enhance power output and efficiency, with insights into optimal transmission shapes.

Contribution

It introduces a quantum transport model with B"uttiker probes to simulate energy-loss processes in hot-carrier solar cells, providing new analysis of efficiency and power.

Findings

Nonequilibrium carrier extraction can improve efficiency and power.

Boxcar-shaped transmission maximizes efficiency in thermal limit.

Partial efficiencies quantify different loss process impacts.

Abstract

In conventional solar cells, photogenerated carriers lose part of their energy before they can be extracted to make electricity. The aim of hot-carrier solar cells is to extract the carriers before this energy loss, thereby turning more energy into electrical power. This requires extracting the carriers in a nonequilibrium (nonthermal) energy distribution. Here, we investigate the performance of hot-carrier solar cells for such nonequilibrium distributions. We propose a quantum transport model in which each energy-loss process (carrier thermalization, relaxation, and recombination) is simulated by a B\"uttiker probe. We study charge and heat transport to analyze the hot-carrier solar cell's power output and efficiency, introducing partial efficiencies for different loss processes and the carrier extraction. We show that producing electrical power from a nonequilibrium distribution has the potential to improve the output power and efficiency. Furthermore, in the limit where the distribution is thermal, we prove that a boxcar-shaped transmission for the carrier extraction maximizes the efficiency at any given output power.