title: Tuning polymorphism and orientation in organic semiconductor thin films via post-deposition processing.
abstract: Though both the crystal structure and molecular orientation of organic semiconductors are known to impact charge transport in thin-film devices, separately accessing different polymorphs and varying the out-of-plane molecular orientation is challenging, typically requiring stringent control over film deposition conditions, film thickness, and substrate chemistry. Here we demonstrate independent tuning of the crystalline polymorph and molecular orientation in thin films of contorted hexabenzocoronene, c-HBC, during post-deposition processing without the need to adjust deposition conditions. Three polymorphs are observed, two of which have not been previously reported. Using our ability to independently tune the crystal structure and out-of-plane molecular orientation in thin films of c-HBC, we have decoupled and evaluated the effects that molecular packing and orientation have on device performance in thin-film transistors (TFTs). In the case of TFTs comprising c-HBC, polymorphism and molecular orientation are equally important; independently changing either one affects the field-effect mobility by an order of magnitude.
authors.affiliation: Department of Chemical and Biological Engineering, Princeton University , A323 Engineering Quadrangle, Princeton, New Jersey 08544, United States.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Hiszpanski
authors.forename: Robin M
authors.initials: RM
authors.lastname: Baur
authors.forename: Bumjung
authors.initials: B
authors.lastname: Kim
authors.forename: Noah J
authors.initials: NJ
authors.lastname: Tremblay
authors.forename: Colin
authors.initials: C
authors.lastname: Nuckolls
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Woll
authors.forename: Yueh-Lin
authors.initials: YL
authors.lastname: Loo
mesh_terms: D009930:Organic Chemicals / Q000737:chemistry*; D012666:Semiconductors; D014961:X-Ray Diffraction
chemical_list: D009930:Organic Chemicals