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dc.contributor.authorWu, Wei-Ruen_US
dc.contributor.authorSu, Chun-Jenen_US
dc.contributor.authorChuang, Wei-Tsungen_US
dc.contributor.authorHuang, Yen-Chihen_US
dc.contributor.authorYang, Po-Weien_US
dc.contributor.authorLin, Po-Changen_US
dc.contributor.authorChen, Chun-Yuen_US
dc.contributor.authorYang, Tsung-Yuen_US
dc.contributor.authorSu, An-Chungen_US
dc.contributor.authorWei, Kung-Hwaen_US
dc.contributor.authorLiu, Chih-Mingen_US
dc.contributor.authorJeng, U-Seren_US
dc.description.abstractThis study provides new evidence on a long postulated mechanism of phase separation in a polymer/fullerene mixture during spin coating for controlled nanodomains of oriented crystallization and heterojunctions that favor applications in polymer solar cells (PSCs). The simultaneous nanoscale phase separation and crystallization during spin coating of the mixture are traced using in situ grazing-incidence small-and wide-angle X-ray scattering. Combined with the complimentary results from time-resolved optical reflectance spectroscopy, transient stratification of the liquid film during the transition from the flow-to evaporation-dominated stage of spin coating is disclosed; the vertical liquid-liquid phase separation incubates a supersaturated skin layer where fullerene aggregation and polymer crystallization occur and develop concomitantly. Shortly after the transition, the near-surface structural development is largely pinned, leaving the solvent-rich bottom layer to diminish via solvent diffusion and evaporation through the thickened skin layer that finally condenses into the spin-coated film upon solvent depletion. The shear-enhanced surface layering and supersaturation for the surface-down nanostructural development are unexpected in all the existing structural models for PSCs. The mechanistic understanding of coupled vertical phase separation and local nanosegregation provides new insights and alternative strategy to the morphology control of spin-cast PSC active layers in particular and various solution-processed polymeric films in general.en_US
dc.titleSurface Layering and Supersaturation for Top-Down Nanostructural Development during Spin Coating of Polymer/Fullerene Thin Filmsen_US
dc.identifier.journalADVANCED ENERGY MATERIALSen_US
dc.contributor.departmentDepartment of Materials Science and Engineeringen_US
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