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Confined and Chemically Flexible Grain Boundaries in Polycrystalline Compound Semiconductors
Author(s) -
AbouRas Daniel,
Schmidt Sebastian S.,
Caballero Raquel,
Unold Thomas,
Schock HansWerner,
Koch Christoph T.,
Schaffer Bernhard,
Schaffer Miroslava,
Choi PyuckPa,
CojocaruMirédin Oana
Publication year - 2012
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201100764
Subject(s) - materials science , crystallite , grain boundary , ionic bonding , thin film , solar cell , semiconductor , chemical physics , optoelectronics , nanotechnology , microstructure , ion , composite material , metallurgy , physics , quantum mechanics
Grain boundaries (GBs) in polycrystalline Cu(In,Ga)Se 2 thin films exhibit only slightly enhanced recombination, as compared with the grain interiors, allowing for very high power‐conversion efficiencies of more than 20% in the corresponding solar‐cell devices. This work highlights the specific compositional and electrical properties of Cu(In,Ga)Se 2 GBs by application of appropriate subnanometer characterisation techniques: inline electron holography, electron energy‐loss spectroscopy, and atom‐probe tomography. It is found that changes of composition at the GBs are confined to regions of only about 1 nm in width. Therefore, these compositional changes are not due to secondary phases but atomic or ionic redistribution within the atomic planes close to the GBs. For different GBs in the Cu(In,Ga)Se 2 thin film investigated, different atomic or ionic redistributions are also found. This chemical flexibility makes polycrystalline Cu(In,Ga)Se 2 thin films particularly suitable for photovoltaic applications.