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Title: Review of grain interior, grain boundary, and interface effects of K in CIGS solar cells: Mechanisms for performance enhancement

Introducing K into Cu(In,Ga)(Se,S) 2 (CIGS) absorbers has led to recent world record power conversion efficiencies for thin film polycrystalline solar cells. In this work, the diverse phenomena associated with K in CIGS were reviewed, and overarching mechanisms were identified. The effects of K depend on its distribution among grain interiors (GIs), grain boundaries (GBs), and interfaces. High substrate Na and low temperature favor GI K incorporation, while low Na and high temperature favor segregation of K at GBs. Depositing KInSe 2 (or KIn 1-yGaySe 2) by co-evaporation or KF post-deposition treatment onto CIGS reduces buffer interface recombination in the final solar cells. KInSe 2 decomposes in air, which makes characterization difficult and may affect performance. In conclusion, the mechanism for reduced interface recombination could be direct passivation, beneficial compound precursor, oxidation barrier, or favorable diffusion alteration.
Authors:
 [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-68981
Journal ID: ISSN 0927-0248
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 172; Journal Issue: C; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; chalcopyrite; Cu(In,Ga)Se2; potassium; alkali metal; KInSe2; K(In,Ga)Se2
OSTI Identifier:
1373683