title: One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films.
abstract: A crystal's structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes.
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Giri
authors.affiliation: 1] Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia [2] Solar and Photovoltaic Engineering Research Center (SPERC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Ruipeng
authors.initials: R
authors.lastname: Li
authors.affiliation: Cornell High Energy Synchrotron Source (CHESS), Ithaca, New York 14853, USA.
authors.forename: Detlef-M
authors.initials: DM
authors.lastname: Smilgies
authors.affiliation: Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Er Qiang
authors.initials: EQ
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Diao
authors.affiliation: School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Lenn
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Melanie
authors.initials: M
authors.lastname: Chiu
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Debora W
authors.initials: DW
authors.lastname: Lin
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Ranulfo
authors.initials: R
authors.lastname: Allen
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Julia
authors.initials: J
authors.lastname: Reinspach
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Stefan C B
authors.initials: SC
authors.lastname: Mannsfeld
authors.affiliation: Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Sigurdur T
authors.initials: ST
authors.lastname: Thoroddsen
authors.affiliation: School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Paulette
authors.initials: P
authors.lastname: Clancy
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Zhenan
authors.initials: Z
authors.lastname: Bao
authors.affiliation: 1] Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia [2] Solar and Photovoltaic Engineering Research Center (SPERC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Aram
authors.initials: A
authors.lastname: Amassian
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D004581:Electronics; D061848:Optical Imaging; D017646:Organosilicon Compounds; D012666:Semiconductors
chemical_list: D017646:Organosilicon Compounds; C522282:bis(triisopropylsilylethynyl)pentacene