Thermo-photo-voltaic energy conversion

The concept of a thermo-photo-voltaic (TPV) energy converter is introduced and the device compared with thermoelectric and thermionic converters. Features of the TPV converter are that the entire device is kept at room temperature; potential power densities on the order of 10 w/cm², and potential conversion efficiencies of 30 per cent are possible. Considerations for TPV converter design are presented and compared with solar cells. Use of geometry and thin-film optical filters to improve efficiency is discussed. For a germanium converter operating with a hot source in the neighborhood of 1600°C a p-i-n structure with the absorption taking place in the intrinsic base region is shown to give maximum efficiency. A measured efficiency of 4.23 per cent on an experimental converter with 282 mw/cm²incident energy has been achieved.