Hadi Afshari1,Brandon Durant1,Tristan Thrasher1,Logan Abshire1,Vincent Whiteside1,Shun Chan2,Dongyoung Kim2,Sabina Hatch2,Mingchu Tang2,Jeremiah McNatt3,Huiyun Liu2,David Smith4,Ian Sellers1
University of Oklahoma1,University College London2,NASA Glenn Research Center3,Arizona State University4
Hadi Afshari1,Brandon Durant1,Tristan Thrasher1,Logan Abshire1,Vincent Whiteside1,Shun Chan2,Dongyoung Kim2,Sabina Hatch2,Mingchu Tang2,Jeremiah McNatt3,Huiyun Liu2,David Smith4,Ian Sellers1
University of Oklahoma1,University College London2,NASA Glenn Research Center3,Arizona State University4
The high radiation tolerance of GaAs<sub>0.86</sub>Sb<sub>0.14</sub> based solar cells with a bandgap suitable for PV is demonstrated at the low intensity low temperature (LILT) conditions. This system shows remarkable radiation hardness at AM0, and more prominently, at the conditions of several outer planetary targets. The photovoltaic behavior of the system after electron irradiation is attributed to an irradiation induced change in the absorber bandgap due to local heating and strain relaxation, and the generation of less prohibitive shallow Sb-based defects in the GaAs<sub>1-x</sub>Sb<sub>x </sub>absorber.<br/>Both high efficiency and radiation tolerance are the two essential factors required for solar cells working in space. While III-V multi-junction solar cells are used ubiquitously in space, the radiation tolerance of such systems, particularly in deep space brings added complexity to their design since there is large variability in the sub cell radiation tolerance. Although, numerous studies have been performed to improve radiation resistance of the tandem structures; still thick cover glass is required, which increases the weight and reduces the specific power of the systems. GaAs as one of the most successful PV technologies has now reached record PCE levels, but its response to high radiation levels under LILT conditions is concerning (particularly around Jupiter and its moons) requiring very thick cover glass which removes the ability for compact stowage and deployment. Recently, ultrathin GaAs has been shown to offer potential as a more radiation hard system for space, if appropriate optical management can be designed to improve the absorption. Here, we propose GaAsSb as an alternative candidate system for space power applications, particularly in the regions of harsh radiation conditions of outer space and under LILT conditions. We show remarkably radiation tolerant performance in optically thick optimized GaAs<sub>0.86</sub>Sb<sub>0.14</sub> without encapsulation suggesting this material should be further considered for hostile space missions including those to Jupiter or for satellite applications in Highly Eccentric Orbits (HEO) being considered to provide better internet coverage which require more robust systems than are currently available.