Ultra Fast and Parsimonious Materials Screening for Polymer Solar Cells Using Differentially Pumped Slot-Die Coating

Jan Alstrup, Mikkel Jørgensen, Andrew James Medford, Frederik C Krebs

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    We present a technique that enables the probing of the entire parameter space for each parameter with good statistics through a simple roll-to-roll processing method where gradients of donor, acceptor, and solvent are applied by differentially pumped slot-die coating. We thus demonstrate how the optimum donor−acceptor ratio and device film thickness can be determined with improved accuracy by varying the composition in small steps. We give as an example P3HT-PCBM devices and vary the composition between P3HT and PCBM in steps of 0.5−1% giving 100−200 individual solar cells. The coating experiment itself takes less than 4−8 min and requires 15−30 mg each of donor and acceptor material. The optimum donor−acceptor composition of P3HT and PCBM was found to be a broad maximum centered on a 1:1 ratio. We demonstrate how the optimal thickness of the active layer can be found by the same method and materials usage by variation of the layer thickness in small steps of 1.5−4 nm. Contrary to expectation we did not find oscillatory variation of the device performance with device thickness because of optical interference. We ascribe this to the nature of the solar cell type explored in this example that employs nonreflective or semitransparent printed electrodes. We further found that very thick active layers on the order of 1 μm can be prepared without loss in performance and estimate the active layer thickness could easily approach 4−5 μm while maintaining photovoltaic properties.
    Original languageEnglish
    JournalA C S Applied Materials and Interfaces
    Volume2
    Issue number10
    Pages (from-to)2819-2827
    ISSN1944-8244
    DOIs
    Publication statusPublished - 2010

    Bibliographical note

    This work was supported
    by the Danish Strategic Research Council (DSF 2104-
    05-0052 and 2104-07-0022) and EUDP (j. nr. 64009-0050).
    A patent application covering the inventions described in this
    article has been filed.

    Keywords

    • Polymer solar cells
    • Solar energy

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