University of Oulu

ACS Appl. Energy Mater.2018, 1, 11, 5977-5985. Publication Date: October 8, 2018.

Effect of the electron transport layer on the interfacial energy barriers and lifetime of R2R printed organic solar cell modules

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Author: Vilkman, Marja1; Väisänen, Kaisa-Leena2; Apilo, Pälvi2;
Organizations: 1VTT Technical Research Centre of Finland, Tietotie 3, P.O. Box 1000, FI-02150 Espoo, Finland
2VTT Technical Research Centre of Finland, Kaitoväylä 1, P.O. Box 1100, FI-90571 Oulu, Finland
3Eni S.p.A, Renewable Energy & Environmental R&D, Via Fauser 4, 28100 Novara, Italy
4Department of Applied Physics, Aalto School of Science, P.O. Box 15100, FI-00076 Aalto, Finland
5University of Oulu, Center of Microscopy and Nanotechnology, Erkki-Koisokanttilan katu 3, P.O. Box 7150, FI-90570 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 6.2 MB)
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Language: English
Published: American Chemical Society, 2018
Publish Date: 2019-07-08


Understanding the phenomena at interfaces is crucial for producing efficient and stable flexible organic solar cell modules. Minimized energy barriers enable efficient charge transfer, and good adhesion allows mechanical and environmental stability and thus increased lifetime. We utilize here the inverted organic solar module stack and standard photoactive materials (a blend of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester) to study the interfaces in a pilot scale large-area roll-to-roll (R2R) process. The results show that the adhesion and work function of the zinc oxide nanoparticle based electron transport layer can be controlled in the R2R process, which allows optimization of performance and lifetime. Plasma treatment of zinc oxide (ZnO) nanoparticles and encapsulation-induced oxygen trapping will increase the absolute value of the ZnO work function, resulting in energy barriers and an S-shaped IV curve. However, light soaking will decrease the zinc oxide work function close to the original value and the S-shape can be recovered, leading to power conversion efficiencies above 3%. We present also an electrical simulation, which supports the results. Finally, we study the effect of plasma treatment in more detail and show that we can effectively remove the organic ligands around the ZnO nanoparticles from the printed layer in a R2R process, resulting in increased adhesion. This postprinting plasma treatment increases the lifetime of the R2R printed modules significantly with modules retaining 80% of their efficiency for ∼3000 h in accelerated conditions. Without plasma treatment, this efficiency level is reached in less than 1000 h.

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Series: ACS applied energy materials
ISSN: 2574-0962
ISSN-E: 2574-0962
ISSN-L: 2574-0962
Volume: 1
Issue: 11
Pages: 5977 - 5985
DOI: 10.1021/acsaem.8b01040
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: The authors acknowledge financial support from Eni S.p.A and VTT Technical Research Centre of Finland LtD.
Copyright information: © 2018 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.