Improved energy conversion efficiency in wide-bandgap Cu(In,Ga)Se2 solar cells
Subtitle: preprint
By: Miguel Contreras ... [et al.].
Contributors: National Renewable Energy Laboratory (U.S.); IEEE Photovoltaic Specialists Conference (37th : 2011 : Seattle, Wash.)
Series: NREL/CP -- 5200-50669; Conference paper (National Renewable Energy Laboratory (U.S.)) -- NREL/CP-5200-50669.
Publisher: National Renewable Energy Laboratory
Published: 2011
Place of publication: Golden, CO]
Language: eng
Format: [electronic resource] :
Subjects: Photovoltaic power systems; Research; Solar cells; Design and construction
Description: This report outlines improvements to the energy conversion efficiency in wide bandgap (Eg>1.2 eV) solar cells based on CuIn1-xGaxSe2. Using (a) alkaline containing high temperature glass substrates, (b) elevated substrate temperatures 600-650 degrees C and (c) high vacuum evaporation from elemental sources following NREL's three-stage process, we have been able to improve the performance of wider bandgap solar cells with 1.2<Eg<1.45 eV. Initial results of this work have led to efficiencies >18% for absorber bandgaps ~1.30 eV and efficiencies ~16% for bandgaps up to ~1.45 eV. In comparing J-V parameters in similar materials, we establish gains in the open-circuit voltage and, to a lesser degree, the fill factor value, as the reason for the improved performance. The higher voltages seen in these wide gap materials grown at high substrate temperatures may be due to reduced recombination at the grain boundary of such absorber films. Solar cell results, absorber materials characterization, and experimental details are reported.
Notes: Title from title screen (viewed August 1, 2011).

"July 2011."

"Presented at the 37th IEEE Photovoltaic Specialists Conference (PVSC 37), Seattle, Washington, June 19-24, 2011."

Includes bibliographical references (p. 6).

DE-AC36-08GO28308

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