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Title: Comparison of CIGS solar cells made with different structures and fabrication techniques

Cu(In, Ga)Se2 (CIGS)-based solar cells from six fabricators were characterized and compared. The devices had differing substrates, absorber deposition processes, buffer materials, and contact materials. The effective bandgaps of devices varied from 1.05 to 1.22 eV, with the lowest optical bandgaps occurring in those with metal-precursor absorber processes. Devices with Zn(O, S) or thin CdS buffers had quantum efficiencies above 90% down to 400 nm. Most voltages were 250-300 mV below the Shockley-Queisser limit for their bandgap. Electroluminescence intensity tracked well with the respective voltage deficits. Fill factor (FF) was as high as 95% of the maximum for each device's respective current and voltage, with higher FF corresponding to lower diode quality factors (~1.3). An in-depth analysis of FF losses determined that diode quality reflected in the quality factor, voltage-dependent photocurrent, and, to a lesser extent, the parasitic resistances are the limiting factors. As a result, different absorber processes and device structures led to a range of electrical and physical characteristics, yet this investigation showed that multiple fabrication pathways could lead to high-quality and high-efficiency solar cells.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Colorado State Univ., Fort Collins, CO (United States)
  3. Univ. of Delaware, Newark, DE (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-66492
Journal ID: ISSN 2156-3381
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2156-3381
Publisher:
IEEE
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; auger electron spectroscopy (AES); capacitance; characterization; correlation; Cu(In,Ga)Se2 (CIGS); internal quantum efficiency; thin-film photovoltaics
OSTI Identifier:
1357739