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Title: Back reflectors based on buried Al{sub 2}O{sub 3} for enhancement of photon recycling in monolithic, on-substrate III-V solar cells

Photon management has been shown to be a fruitful way to boost the open circuit voltage and efficiency of high quality solar cells. Metal or low-index dielectric-based back reflectors can be used to confine the reemitted photons and enhance photon recycling. Gaining access to the back of the solar cell for placing these reflectors implies having to remove the substrate, with the associated added complexity to the solar cell manufacturing. In this work, we analyze the effectiveness of a single-layer reflector placed at the back of on-substrate solar cells, and assess the photon recycling improvement as a function of the refractive index of this layer. Al{sub 2}O{sub 3}-based reflectors, created by lateral oxidation of an AlAs layer, are identified as a feasible choice for on-substrate solar cells, which can produce a V{sub oc} increase of around 65% of the maximum increase attainable with an ideal reflector. The experimental results obtained using prototype GaAs cell structures show a greater than two-fold increase in the external radiative efficiency and a V{sub oc} increase of ∼2% (∼18 mV), consistent with theoretical calculations. For GaAs cells with higher internal luminescence, this V{sub oc} boost is calculated to be up to 4% relative (36 mV), which directlymore » translates into at least 4% higher relative efficiency.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ; ; ; ;  [1]
  1. National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)
  2. (Spain)
  3. (United States)
Publication Date:
OSTI Identifier:
22350827
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 13; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM ARSENIDES; ALUMINIUM OXIDES; DIELECTRIC MATERIALS; EFFICIENCY; ELECTRIC POTENTIAL; GAIN; GALLIUM ARSENIDES; LAYERS; LUMINESCENCE; MANAGEMENT; MANUFACTURING; METALS; OXIDATION; PHOTONS; REFRACTIVE INDEX; SOLAR CELLS; SOLAR REFLECTORS; SUBSTRATES