Metamorphic and Lattice-Matched GaInP Rear-Heterojunction Solar Cells for Improved Performance at Elevated Temperatures

We present the characteristics of n-on-p front-junction (FJ) and rear-heterojunction (RHJ) GaInP solar cells at operating temperatures (T) up to 300 degree celsius. Photovoltaic cells with efficient operation at high T may be important for satellite missions near the sun or as laser power converters for sensors operating in harsh environments. In this article, we show that the time-resolved photoluminescence lifetime (tau(TRPL)) values in both lattice-matched (LM) n-Ga0.51In0.49P and metamorphic (MM) n-Ga0.37In0.63P double heterostructures are high and increase significantly with T. In contrast, the tau(TRPL) values in their p-type counterparts are lower and decrease with T. We go on to demonstrate both LM and MM solar cells in FJ and RHJ configurations. The internal quantum efficiency (IQE) of MM RHJ cells increases significantly up to T = 300 degree celsius due to the increase in both tau(TRPL) and the linear increase in diffusivity with T. In contrast, the IQE for MM FJ cells is nearly unchanged as T increases, while the IQE of LM cells drops sharply across all wavelengths. RHJ cells maintain higher open-circuit voltage and fill factor than their FJ counterparts, leading to a significant efficiency advantage at T = 100-300 degree celsius. Taken together, our work shows that MM cells perform well at elevated T and that RHJ cells are promising for high-T operation.