Thermo-photo-voltaic conversion from high temperature energy sources

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 watts/cm³, and potential conversion efliciencies of 30 percent. 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 percent on an experimental converter with 282 mw/cm²incident energy has been achieved.