III–V Laser Power Converters With Vertically Stacked Subcells Demonstrating Superior Radiation Resilience

Photovoltaic cells are detrimentally impacted by exposure to ionizing radiation, a consideration of particular significance for applications in outer space. In this paper, we demonstrate that vertical epitaxial heterostructure architecture (VEHSA) laser power converters are particularly resilient toward radiation-induced degradation; in particular, we observed reductions in efficiency of 1.9% and 6.4% for 5- and 20-junction monolithic devices, respectively, at near 3 W of input power (V
_oc
of 5.78 and 23.32 V and peak response near 850 nm). This contrasts markedly with the 16.9% and 25.4% reductions in efficiency for the same 5- and 20-junction devices when using a detuned source at 808 nm, which we attribute to a reduction in nonradiative recombination lifetimes leading to a suppression of radiative recombination driven photon recycling.