Optoelectronic Reciprocity in Hot Carrier Solar Cells with Ideal Energy Selective Contacts

TL;DR

This paper explores the experimental signatures of hot carrier solar cells, focusing on how their electro-luminescence and dark current characteristics deviate from conventional models, influenced by carrier temperature and Auger processes.

Contribution

It introduces a framework to identify hot carrier behavior through electro-luminescence and dark I-V measurements, highlighting the effects of Auger processes on device signatures.

Findings

Deviations from Shockley diode equation indicate hot carrier effects.

Carrier temperature increases are observable via electro-luminescence spectra.

Hot carrier behavior varies significantly with Auger recombination regimes.

Abstract

Hot carrier solar cells promise theoretical power conversion efficiencies far beyond the single junction limit. However, practical implementations of hot carrier solar cells have lagged far behind those theoretical predictions. Reciprocity relations for electro-luminescence from conventional single junction solar cells have been extremely successful in driving their efficiency ever closer to the theoretical limits. In this work, we discuss how the signatures of a functioning hot carrier device should manifest experimentally in electro-luminescence and dark $I-V$ characteristics. Hot carrier properties lead to deviations from the Shockley diode equation that is typical for conventional single junction solar cells. These deviations are directly linked to an increase in temperature of the carriers and therefore the temperature measured from electro-luminescence spectra. We also elucidate how the behaviour of hot carrier solar cells in the dark depends on whether Auger processes play a significant role, revealing a stark contrast between the regime of negligible Auger recombination (carrier conservation model) and dominant Auger recombination (Impact Ionization model) for hot carrier solar cells.