Conversion-efficiency mark is a world record for a two-junction solar cell measured under one-sun illumination
The Energy Department’s National Renewable Energy Lab has announced a world record of 31.1% conversion efficiency for a two-junction solar cell under one sun of illumination.
NREL Scientist Myles Steiner announced the new record June 19 at the 39th IEEE Photovoltaic Specialists Conference in Tampa, Fla. The previous record of 30.8% efficiency was held by Alta Devices.
The tandem cell was made of a gallium indium phosphide cell atop a gallium arsenide cell, has an area of about 0.25 square centimeters and was measured under the AM1.5 global spectrum at 1,000 W/m2. It was grown inverted, similar to the NREL-developed inverted metamorphic multi-junction (IMM) solar cell – and flipped during processing. The cell was covered on the front with a bilayer anti-reflection coating, and on the back with a highly reflective gold contact layer.