Keller, D, Buecheler, S, Reinhard, P et al. (7 more authors) (2016) Band gap widening at random CIGS grain boundary detected by valence electron energy loss spectroscopy. Applied Physics Letters, 109 (15). 153103. ISSN 0003-6951
Abstract
Cu(In,Ga) Se₂ (CIGS) thin film solar cells have demonstrated very high efficiencies, but still the role of nanoscale inhomogeneities in CIGS and their impact on the solar cell performance are not yet clearly understood. Due to the polycrystalline structure of CIGS, grain boundaries are very common structural defects that are also accompanied by compositional variations. In this work, we apply valence electron energy loss spectroscopy in scanning transmission electron microscopy to study the local band gap energy at a grain boundary in the CIGS absorber layer. Based on this example, we demonstrate the capabilities of a 2nd generation monochromator that provides a very high energy resolution and allows for directly relating the chemical composition and the band gap energy across the grain boundary. A band gap widening of about 20 meV is observed at the grain boundary. Furthermore, the compositional analysis by core-loss EELS reveals an enrichment of In together with a Cu, Ga and Se depletion at the same area. The experimentally obtained results can therefore be well explained by the presence of a valence band barrier at the grain boundary.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 Author(s). Reproduced in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 11 Jan 2019 14:26 |
Last Modified: | 11 Jan 2019 14:26 |
Status: | Published |
Publisher: | AIP publishing |
Identification Number: | 10.1063/1.4964516 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140913 |