Compact Roll-to-Roll Coater for in Situ X-ray Diffraction Characterization of Organic Electronics Printing

Xiaodan Gu, Julia Reinspach, Brian J. Worfolk, Ying Diao, Yan Zhou, Hongping Yan, Kevin Gu, Stefan Mannsfeld, Michael F. Toney, Zhenan Bao

Research output: Contribution to journalArticlepeer-review


We describe a compact roll-to-roll (R2R) coater that is capable of tracking the crystallization process of semiconducting polymers during solution printing using X-ray scattering at synchrotron beamlines. An improved understanding of the morphology evolution during the solution-processing of organic semiconductor materials during R2R coating processes is necessary to bridge the gap between "lab" and "fab". The instrument consists of a vacuum chuck to hold the flexible plastic substrate uniformly flat for grazing incidence X-ray scattering. The time resolution of the drying process that is achievable can be tuned by controlling two independent motor speeds, namely, the speed of the moving flexible substrate and the speed of the printer head moving in the opposite direction. With this novel design, we are able to achieve a wide range of drying time resolutions, from tens of milliseconds to seconds. This allows examination of the crystallization process over either fast or slow drying processes depending on coating conditions. Using regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) inks based on two different solvents as a model system, we demonstrate the capability of our in situ R2R printing tool by observing two distinct crystallization processes for inks drying from the solvents with different boiling points (evaporation rates). We also observed delayed on-set point for the crystallization of P3HT polymer in the 1:1 P3HT/PCBM BHJ blend, and the inhibited crystallization of the P3HT during the late stage of the drying process.

Original languageEnglish (US)
Pages (from-to)1687-1694
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number3
StatePublished - Jan 27 2016


  • X-ray scattering
  • organic electronics
  • roll-to-roll process
  • solar cell
  • synchrotron radiation

ASJC Scopus subject areas

  • General Materials Science


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