Mismatched InGaAs photovoltaic devices thermophotovoltaic power systems

Low bandgap photovoltaic devices are required for the development of thermophotovoltaic power conversion at moderate temperatures. We have produced In/sub x/Ga/sub 1-x/As photovoltaic n/p devices on InP with bandgaps ranging from 0.75 eV to 0.60 eV. Testing under a filtered 1500/spl deg/K blackbody emitter, the 0.75 eV displayed an 18.3% conversion efficiency and the 0.60 eV device had a 6% efficiency. The devices were also tested at temperatures ranging from 25/spl deg/C to 100/spl deg/C. The temperature coefficient of output power increased dramatically as the bandgap decreased. Testing under rare-earth doped YAG selective emitters demonstrated the ability of these emitters to produce narrow spectral emissions.