  Optimal radiator thermal emission spectra maximizing thermophotovoltaic (TPV)
conversion efficiency and output power density are determined when temperature
effects in the cell are considered. To do this, a framework is designed in
which a TPV model that accounts for radiative, electrical and thermal losses is
coupled with a genetic algorithm. The TPV device under study involves a
spectrally selective radiator at a temperature of 2000 K, a gallium antimonide
cell, and a cell thermal management system characterized by a fluid temperature
and a heat transfer coefficient of 293 K and 600 Wm-2K-1. It is shown that a
maximum conversion efficiency of 38.8% is achievable with an emission spectrum
that has emissivity of unity between 0.719 eV and 0.763 eV and zero elsewhere.
This optimal spectrum is less than half of the width of those when thermal
losses are neglected. A maximum output power density of 41708 Wm-2 is
achievable with a spectrum having emissivity values of unity between 0.684 eV
and 1.082 eV and zero elsewhere when thermal losses are accounted for. These
emission spectra are shown to greatly outperform blackbody and tungsten
radiators, and could be obtained using artificial structures such as
metamaterials or photonic crystals.
