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Ultra-fast determination of quantum efficiency of a solar cell

United States Patent

August 7, 2012
View the Complete Patent at the US Patent & Trademark Office
National Renewable Energy Laboratory - Visit the NREL Technology Transfer Website
Ultra-Fast Quantum Efficiency Solar Cell Test
An apparatus for measuring quantum efficiency (QE) of solar cells. The apparatus includes a light source including an array of light emitting diodes (LEDs) that each emit light corresponding to a differing portion of a test spectrum and each LED is driven by a sinusoidal power supply that operates at a unique frequency. The light source includes an optical coupling focusing the LED light into a test beam targeted on a solar cell, and a signal conditioner converts analog current signals generated by the solar cell into digital voltage signals. A QE measurement module determines a QE value corresponding to each of the LEDs based on the digital voltage signals using a Fast Fourier Transform module that processes the digital voltage signals to generate values for each operating frequency. The QE measurement module determines the QE values by applying a conversion factor to these values. Since all the LEDs can be power-modulated simultaneously and the corresponding cell responses to each of the LEDS can be analyzed simultaneously, the QE spectrum measurement time is greatly shortened as compared to conventional methods.
Young; David L. (Golden, CO), Egaas; Brian (Golden, CO), Stradins; Pauls (Golden, CO)
Alliance for Sustainable Energy, LLC (Golden, CO)
12/ 237,452
September 25, 2008
CONTRACTUAL ORIGIN The United States Government has rights in this invention under contact No. DE-AC36-99GO10337 between the United States Department of Energy and the National Renewable Energy Laboratory, a Division of the Midwest Research Institute.