Selective emitters for thermophotovoltaic energy converters-a study based on material prospects

A thermophotovoltaic (TPV) energy converter is a system used to convert thermal energy to electric energy. The system consists of a thermally excited photon emitter and photovoltaic (PV) cell. A thermally excited selective line emitter (rare earth oxide emitter) is a photon source which provides photons at elevated temperatures with a narrow energy band that can be matched with the PV cell bandgap energy. The PV cells can then convert photon energy to electricity at high efficiency. Past research on fibrous rare earth oxide selective emitters has shown that high emitter efficiency was attained at the expense of emitter mechanical strength. Therefore, an improvement of the emitter strength without sacrificing its emitter efficiency becomes one of the key issues in TPV research. This paper describes novel material processing approaches to produce reasonably strong rare earth emitters with high efficiency. The effect of the amount of rare-earth oxide and the material structure (fibrous and solid) on the selective efficiency of the emitters has been addressed in some detail