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Proceedings Paper

Thin film Cu(In,Ga)Se2 materials and devices: a versatile material for flat-plate and concentrator photovoltaic applications
Author(s): John R. Tuttle; M. A. Contreras; J. S. Ward; A. L. Tennant; K. R. Ramanathan; J. Keane; R. N. Noufi
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Paper Abstract

Thin-film Cu(In,Ga)Se2(CIGS) is used as the absorber in an all-thin-film solar cell for both conventional 1-sun and concentrator applications. The absorber fabrication process is represented by time-dependent profiles of elemental Cu, In, Ga, and Se fluxes. The Cu/(In+Ga) ratio determines the phase chemistry during growth whereas the Ga/(Ga+In) ratio determines the CIGS band gap profile. All film-growth processes enter the CIGS:CuxSe two-phase field where the CuxSe facilitates large grain growth. Characterization of cells under 1-sun illumination reveals world-record total-area performance of 17.1%. Improvements relative to previous cells are linked to decreased inter-diffusion of In and Ga within the absorber. Cell parameters include an open-circuit voltage (Voc) of 654 mV and short-circuit current (Jsc) of 33.9 mA/cm2. A second cell was fabricated for operation under concentration. The 1-sun, direct-spectrum measurement yielded at 15.1%- efficient cell. Under 5- and 22-sun concentration, the cell improved to 16.5% and 17.2%, respectively. This achievement is significant in that it proves a compatibility of polycrystalline thin-film and concentrator technologies. Further optimization could yield 1-sun performance in excess of 18% and concentrator performance in excess of 20%. A path to this goal is outlined.

Paper Details

Date Published: 23 August 1995
PDF: 7 pages
Proc. SPIE 2531, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV, (23 August 1995); doi: 10.1117/12.217333
Show Author Affiliations
John R. Tuttle, National Renewable Energy Lab. (United States)
M. A. Contreras, National Renewable Energy Lab. (United States)
J. S. Ward, National Renewable Energy Lab. (United States)
A. L. Tennant, National Renewable Energy Lab. (United States)
K. R. Ramanathan, National Renewable Energy Lab. (United States)
J. Keane, National Renewable Energy Lab. (United States)
R. N. Noufi, National Renewable Energy Lab. (United States)


Published in SPIE Proceedings Vol. 2531:
Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIV
Carl M. Lampert; Satyen K. Deb; Claes-Goeran Granqvist, Editor(s)

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