Can Thermodynamics Guide Us to Make Better Solar Cells?

Thermodynamics has provided a powerful tool to study radiation and its conversion into useful work. Starting from the so-called Shockley's paradox, this article discusses the thermodynamic view of fundamental losses to photovoltaic conversion, and how thermodynamics enters the charge-carrier transport in semiconductors and heat-exchange processes at p-n junctions. Turning to photon flows, considerations based on detailed balance and reciprocity provide a comprehensive picture of the voltage produced by the solar cell in the presence of nonradiative recombination. We shall use these tools to examine several topics under recent discussion, including photon recycling and hot-carrier conversion based on thermoelectricity.