Bouzid, F.Maamri, N.2020-10-202020-10-202012-07-01Articale in Journal of fundamental and Applied Sciences Vol. 04 N. 021112-9867http://dspace.univ-eloued.dz/handle/123456789/7179Articale in Journal of fundamental and Applied Sciences Vol. 04 N. 02In this paper,we investigated the heat to electricity conversion efficiency of In1-xGaxAsySb1-yradioisotope thermophotovoltaic (RTPV) converter with x=0.8 and y=0.18, taking account of the photons with energy below the cells bandgap using a comprehensive analytical process. This was done with a computer program designed for this reason, which allowed the computation of the cell performance under a variety of specified incident radiation spectra as well as a variety of material parameters. The results show that for an emissivity value of 0.78, a cell thickness of about 7µm with low front recombination velocity(700cm/s),a conversion efficiency greater than 29% can be obtained for radiator’s temperature of1300°k at ambient temperature. This efficiency will decrease as the cell temperature increase.enRadioisotope,Emissivity,Recombination velocity, Efficiency, Temperature.Article