Existing solar energy technology usually takes one of two forms, a 'quantum' approach, as in photovoltaic cells, and a 'thermal' approach, which uses concentrated sunlight as a source of thermal energy for a heat engine. Photon-enhanced thermionic emission (PETE) is a new concept for solar electricity generation, which directly combines these disparate quantum and thermal mechanisms into a single physical process, potentially overcoming the losses inherent to photovoltaic cells while bypassing some of the challenges faced by traditional thermal methods. Unlike conventional photovoltaic cells, the PETE process works most efficiently at high temperatures, creating unique opportunities to be used as a high-temperature topping cycle to increase the efficiency of existing solar thermal devices.
The PETE process is based on the thermionic emission of electrons excited by solar photons within a semiconductor at high temperature. Our lab first demonstrated the PETE process and has subsequently designed a novel heterostructure architecture that breaks the emission process into two parts, internal PETE and external emission into vacuum. Our approach is to study each process individually using this structure in order to separately optimize the efficiency of internal PETE and vacuum emission, with the ultimate goal of creating highly efficient solar conversion that can contribute to the world's energy needs.
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