Heterogeneous nucleation promotes carrier transport in solution-processed organic field-effect transistors
Khan, Hadayat Ullah
Payne, Marcia M.
Smilgies, Detlef Matthias
Anthony, John Edward
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
KAUST Solar Center (KSC)
Materials Science and Engineering Program
Organic Electronics and Photovoltaics Group
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AbstractA new way to investigate and control the growth of solution-cast thin films is presented. The combination of in situ quartz crystal microbalance measurements with dissipation capabilities (QCM-D) and in situ grazing-incidence wide-angle X-ray scattering (GIWAXS) in an environmental chamber provides unique quantitative insights into the time-evolution of the concentration of the solution, the onset of nucleation, and the mode of growth of the organic semiconductor under varied drying conditions. It is demonstrated that careful control over the kinetics of solution drying enhances carrier transport significantly by promoting phase transformation predominantly via heterogeneous nucleation and sustained surface growth of a highly lamellar structure at the solid-liquid interface at the expense of homogeneous nucleation. A new way to investigate and control the growth of drop-cast thin films is presented. The solution-processing of small-molecule thin films of TIPS-pentacene is investigated using time-resolved techniques to reveal the mechanisms of nucleation and growth leading to solid film formation. By tuning the drying speed of the solution, the balance between surface and bulk growth modes is altered, thereby controlling the lamellar formation and tuning the carrier mobility in organic field-effect transistors Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
SponsorsThe authors are grateful to Mr. Mohammed Balamesh for his important contributions to the operational readiness of the Organic Electronics and Photovoltaics Laboratory at King Abdullah University of Science and Technology, where most of this work was performed. Part of this work was supported by KAUST's Office of Competitive Research Funds under award number FIC/2010/04. The authors acknowledge use of the D1 beam line at the Cornell High Energy Synchrotron Source supported by the National Science Foundation (NSF DMR-0225180) and NIH-NIGMS.
JournalAdvanced Functional Materials