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Low Work Function Lacunary Polyoxometalates as Electron Transport Interlayers for Inverted Polymer Solar Cells of Improved Efficiency and Stability
Tountas, Marinos Topal, Yasemin Polydorou, Ermioni Soultati, Anastasia Verykios, Apostolos Kaltzoglou, Andreas Papadopoulos, Theodoros A. Auras, Florian Seintis, Kostas Fakis, Mihalis
Tountas, Marinos
Topal, Yasemin
Polydorou, Ermioni
Soultati, Anastasia
Verykios, Apostolos
Kaltzoglou, Andreas
Papadopoulos, Theodoros A.
Auras, Florian
Seintis, Kostas
Fakis, Mihalis
Advisors
Editors
Other Contributors
EPub Date
Publication Date
2017-06-06
Submitted Date
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Abstract
Effective interface engineering has been shown to play a vital role in facilitating efficient charge-carrier transport, thus boosting the performance of organic photovoltaic devices. Herein, we employ water-soluble lacunary polyoxometalates (POMs) as multifunctional interlayers between the titanium dioxide (TiO2) electron extraction/transport layer and the organic photoactive film to simultaneously enhance the efficiency, lifetime, and photostability of polymer solar cells (PSCs). A significant reduction in the work function (WF) of TiO2 upon POM utilization was observed, with the magnitude being controlled by the negative charge of the anion and the selection of the addenda atom (W or Mo). By inserting a POM interlayer with ∼10 nm thickness into the device structure, a significant improvement in the power conversion efficiency was obtained; the optimized POM-modified poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2- 33 ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]:[6,6]-phenyl-C70 butyric acid methyl ester (PTB7:PC70BM)-based PSCs exhibited an efficiency of 8.07%, which represents a 21% efficiency enhancement compared to the reference TiO2 cell. Similar results were obtained in POM-modified devices based on poly(3-hexylthiophene) (P3HT) with electron acceptors of different energy levels, such as PC70BM or indene-C60 bisadduct (IC60BA), which enhanced their efficiency up to 4.34 and 6.21%, respectively, when using POM interlayers; this represents a 25–33% improvement as compared to the reference cells. Moreover, increased lifetime under ambient air and improved photostability under constant illumination were observed in POM-modified devices. Detailed analysis shows that the improvements in efficiency and stability synergistically stem from the reduced work function of TiO2 upon POM coverage, the improved nanomorphology of the photoactive blend, the reduced interfacial recombination losses, the superior electron transfer, and the more effective exciton dissociation at the photoactive layer/POM/TiO2 interfaces.
Citation
Tountas, M., et. al. (2017). Low Work Function Lacunary Polyoxometalates as Electron Transport Interlayers for Inverted Polymer Solar Cells of Improved Efficiency and Stability. ACS Applied Materials and Interfaces, 9(27), 22773-22787. DOI: 10.1021/acsami.7b04600
Publisher
American Chemical Society
Journal
ACS Applied Materials and Interfaces
Research Unit
DOI
10.1021/acsami.7b04600
PubMed ID
PubMed Central ID
Type
Article
Language
en
Description
This document is the Accepted Manuscript version of a Published Work that appeared in final form in
ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher.
To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acsami.7b04600
Series/Report no.
ISSN
1944-8244
EISSN
1944-8252