Thermionic enhanced solar thermoradiative-photovoltaic conversion

Solar thermoradiative-photovoltaic (TR-PV) conversion is a promising power generation technique due to its flexible architecture. However, the TR-PV converter transforms energy from heat to electrons, then photons, and ultimately back to electrons, resulting in irreversible interconversion losses. This paper attempts to present a novel concept of solar thermionic intermediated thermoradiative-photovoltaic (TRTI-PV) conversion. Thermoradiative photons, as well as thermionic electrons are released and involved between the TR and PV ends, minimizing the irreversible loss of the electron-photon transition. A detailed thermodynamic model in which the nonradiative losses are taken into account is established for solar TRTI-PV conversion. The results demonstrate that the thermionic emission dominates the solar TRTI-PV conversion, with mutual restriction between the TR and PV components. The output power of the TRTI-PV converter rises to 35.54 W/cm² at thermoradiative and photovoltaic bandgaps of 0.3 eV and 0.2 eV, respectively, despite the TR and PV component outputs being 1.67 W/cm² and 3.63 W/cm² respectively, substantially lower than those in TR-PVs. The TRTI-PV converter obtains a solar conversion efficiency of roughly 34.78% at a concentration ratio of 1000, which is 3.24 times that of a single TR-PV converter.