Optimum single-gap solar cells for missions to Mercury

The power supply for space probes is usually based on photovoltaic (PV) systems. The first solar cells used in these systems were single-gap solar cells fabricated with Si and GaAs. Later on, multijunction solar cells (MJSC) based on III–V semiconductors were developed because of their higher efficiency and tolerance to a radiation environment [1]. All these solar cells have been based on semiconductors that fulfill the needs of most near-Earth missions. However, those same semiconductors fail to meet the needs of some other missions involving harsh environments such as high-intensity high-temperature (HIHT) environments [2]. In this work, we investigate which semiconductor material is optimum to implement single-gap solar cells for missions to Mercury, where HIHT conditions are expected. Because solar cell efficiency decreases as temperature increases [3], achieving high-efficiency photovoltaic conversion at HIHT conditions is a big challenge. Previous works have pointed out the need of using wide-bandgap semiconductors to reach this goal [4,5]. In this context, we will study the potential of solar cells based on AlxGa1−xAs, a well-known semiconductor whose physical properties have been extensively investigated. The limiting efficiency of these solar cells performing in near-Mercury missions will be calculated to determine the optimum composition for AlxGa1−xAs