Effect of the Electron Transport Layer on the Interfacial Energy Barriers and Lifetime of R2R Printed Organic Solar Cell Modules

Marja Vilkman (Corresponding Author), Kaisa-Leena Väisänen, Pälvi Apilo, Riccardo Po, Marja Välimäki, Mari Ylikunnari, Andrea Bernardi, Tapio Pernu, Gianni Corso, Jani Seitsonen, Santtu Heinilehto, Janne Ruokolainen, Jukka Hast

    Research output: Contribution to journalArticleScientificpeer-review

    12 Citations (Scopus)


    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 post-printing plasma treatment increases the lifetime of the R2R printed modules significantly with modules retaining 80% of their efficiency for ca. 3000 hours in accelerated conditions. Without plasma treatment, this efficiency level is reached in less than 1000 hours.
    Original languageEnglish
    Pages (from-to)5977-5985
    Number of pages9
    JournalACS Applied Energy Materials
    Issue number11
    Publication statusPublished - 26 Nov 2018
    MoE publication typeNot Eligible


    • organic solar cell modules
    • R2R printing
    • lifetime
    • adhesion
    • energy barrier
    • zinc oxide


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