Heating Up Solar Power
Generation of electricity from solar power either uses the thermal energy to power a heat engine or the energy of each photon to initiate a redox reaction in a photovoltaic cell.
Photon enhanced thermionic emission (PETE), the solar converter
developed by Nicholas Melosh and colleagues, Stanford University, USA,
combines the two approaches to create a photovoltaic cell that can
power a secondary thermal engine with its waste heat. Current
photovoltaic cells only operate at temperatures too low to do this.
Measurements from gallium nitride show strong evidence for
photon-enhanced thermionic emission. Coating a GaN semiconductor with a
thin layer of cesium could allow the device to operate at temperatures
exceeding 200 °C with theoretical conversion efficiencies above 50 %.