skip to main content

DOE PAGESDOE PAGES

Title: Light-trapping and recycling for extraordinary power conversion in ultra-thin gallium-arsenide solar cells

Here, we demonstrate nearly 30% power conversion efficiency in ultra-thin (~200 nm) gallium arsenide photonic crystal solar cells by numerical solution of the coupled electromagnetic Maxwell and semiconductor drift-diffusion equations. Our architecture enables wave-interference-induced solar light trapping in the wavelength range from 300-865 nm, leading to absorption of almost 90% of incoming sunlight. Our optimized design for 200 nm equivalent bulk thickness of GaAs, is a square-lattice, slanted conical-pore photonic crystal (lattice constant 550 nm, pore diameter 600 nm, and pore depth 290 nm), passivated with AlGaAs, deposited on a silver back-reflector, with ITO upper contact and encapsulated with SiO2. Our model includes both radiative and non-radiative recombination of photo-generated charge carriers. When all light from radiative recombination is assumed to escape the structure, a maximum achievable photocurrent density (MAPD) of 27.6 mA/cm2 is obtained from normally incident AM 1.5 sunlight. For a surface non-radiative recombination velocity of 103 cm/s, this corresponds to a solar power conversion efficiency of 28.3%. When all light from radiative recombination is trapped and reabsorbed (complete photon recycling) the power conversion efficiency increases to 29%. If the surface recombination velocity is reduced to 10 cm/sec, photon recycling is much more effective and the power conversionmore » efficiency reaches 30.6%.« less
Authors:
 [1] ;  [1]
  1. Univ. of Toronto, Toronto, ON (Canada). Dept. of Physics
Publication Date:
OSTI Identifier:
1285868
Grant/Contract Number:
FG02-06ER46347
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Univ. of Toronto, Toronto, ON (Canada)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY efficiency; localization; absorption; devices