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High efficiency quantum well waveguide solar cells and methods for constructing the same

United States Patent

December 30, 2014
View the Complete Patent at the US Patent & Trademark Office
Photon absorption, and thus current generation, is hindered in conventional thin-film solar cell designs, including quantum well structures, by the limited path length of incident light passing vertically through the device. Optical scattering into lateral waveguide structures provides a physical mechanism to increase photocurrent generation through in-plane light trapping. However, the insertion of wells of high refractive index material with lower energy gap into the device structure often results in lower voltage operation, and hence lower photovoltaic power conversion efficiency. The voltage output of an InGaAs quantum well waveguide photovoltaic device can be increased by employing a III-V material structure with an extended wide band gap emitter heterojunction. Analysis of the light IV characteristics reveals that non-radiative recombination components of the underlying dark diode current have been reduced, exposing the limiting radiative recombination component and providing a pathway for realizing solar-electric conversion efficiency of 30% or more in single junction cells.
Welser; Roger E. (Providence, RI), Sood; Ashok K. (Brookline, MA)
Magnolia Solar, Inc. (Woburn, MA)
13/ 587,530
August 16, 2012
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with U.S. government support under Grant Number NNX11CE59P, awarded by the National Aeronautics and Space Administration (NASA) and Grant Number ERDA1-0000021389 awarded by the New York State Energy Research and Development Authority (NYSERDA). The government may have certain rights in this invention.