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Atomic-layer-deposited aluminum and zirconium oxides for surface passivation of TiO 2 in High-Efficiency Organic Photovoltaics

Vasilopoulou, Maria
; 
Georgiadou, Dimitra G.
; 
Soultati, Anastasia
; 
Boukos, Nikos
; 
Gardelis, Spyros
; 
Palilis, Leonidas C.
; 
Fakis, Mihalis
; 
Skoulatakis, Georgios
; 
Kennou, Stella
; 
Botzakaki, Martha A.
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Affiliation
National Centre for Scientific Research “Demokritos”; University of Patras; University of Munich; University of Bolton; University of Chester
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Publication Date
2014-06-23
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Natural Sciences
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Abstract
The reduction in electronic recombination losses by the passivation of surfaces is a key factor enabling high-efficiency solar cells. Here we investigate a strategy to passivate surface trap states of TiO 2 films used as cathode interlayers in organic photovoltaics (OPVs) through applying alumina (Al2O3) or zirconia (ZrO2) insulating nanolayers by thermal atomic layer deposition (ALD). Our results suggest that the surface traps in TiO 2 are oxygen vacancies, which cause undesirable recombination and high electron extraction barrier, reducing the open-circuit voltage and the short-circuit current of the complete OPV device. It was found that the ALD metal oxides enable excellent passivation of the TiO2 surface followed by a downward shift of the conduction band minimum. OPV devices based on different photoactive layers and using the passivated TiO2 electron extraction layers exhibited a significant enhancement of more than 30% in their power conversion efficiencies (PCEs) as compared to their reference devices without the insulating metal oxide nanolayers as a result of significant suppression of charge recombination and enhanced electron extraction rates at the TiO2/ALD metal-oxide/organic interface.
Citation
Vasilopoulou, M., Georgiadou, D. G., Soultati, A., Boukos, N., Gardelis, S., Palilis, L. C., Fakis, M., Skoulatakis, G., Kennou, S., Botzakaki, M., Georga, S., Krontiras, C. A., Auras, F., Fattakhova-Rohlfing, D., Bein, T., Papadopoulos, T. A., Davazoglou, D., & Argitis, P. (2014). Atomic-Layer-Deposited Aluminum and Zirconium Oxides for Surface Passivation of TiO2 in High-Efficiency Organic Photovoltaics. Advanced Energy Materials, 4(15), 1400214. doi: 10.1002/aenm.201400214
Publisher
Wiley
Journal
Advanced Energy Materials
Research Unit
URI
http://hdl.handle.net/10034/558307
DOI
10.1002/aenm.201400214
PubMed ID
PubMed Central ID
Type
Article
Language
en_US
Description
Series/Report no.
ISSN
1614-6832
EISSN
1614-6840
ISBN
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Sponsors
European Social Fund (ESF) and Greek national funds via the Research Funding Program ARCHIMEDES III.
Additional Links
http://doi.wiley.com/10.1002/aenm.201400214