Thermodynamic Performance of Hot-Carrier Solar Cells: A Quantum Transport Model

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 nonequilib-rium (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 pro-cess (carrier thermalization, relaxation, and recombination) is simulated by a Buttiker 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.

Automated summary

Hot-carrier solar cells aim to extract carriers from photogenerated energy before energy loss occurs in conventional solar cells, leading to higher energy conversion efficiency. This study introduces a quantum transport model to simulate carrier thermalization, relaxation, and recombination using Buttiker probes, and investigates the performance of hot-carrier solar cells with nonequilibrium energy distributions. By analyzing charge and heat transport, partial efficiencies for different loss processes and carrier extraction are introduced to evaluate the power output and efficiency of hot-carrier solar cells. The results show that working with a nonequilibrium energy distribution has the potential to improve power output and efficiency, and a boxcar-shaped transmission for carrier extraction maximizes efficiency at any given output power when the distribution is thermal.