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FOCUS Progress Update - Yale University's High-Temperature Dual-Junction Topping Cells

The project is currently in its second quarter and off to a strong start. In the first quarter, we worked on tasks including: computer modeling of solar cells at elevated temperature; developing metal contacts and anti-reflection coatings that function well at elevated temperature; reliability studies; growth of solar cell materials predicted to offer high efficiency at 400 °C; and Technology to Market (T2M).

One particular task was in testing our custom model that predicts the performance of single-junction solar cells at elevated temperature. Measurements of dark current in III-V solar cells up to 350 °C indicate that the model accurately captures the evolution of dark current as a function of temperature; while measurements up to 200 °C had been attempted before, no data at these high temperatures had been previously available. Another major area of work has been on AlGaInP materials development for the top-cell in our dual-junction device. A range of growth conditions were examined using both metallorganic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE), and initial cell results will be ready by the end of the 2nd quarter.

We have also begun to investigate the electrical and structural properties of metal contacts that are thermally stable while providing low resistance, in addition to dual-layer anti-reflection coatings that are stable and effective at high temperature. Considerable effort has also been put into developing test equipment for assessing both the efficiency and the reliability of the proposed solar cells at 400 °C. 

Progress Updates
May 2015 Progress Update

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