Polymorphism, the ability for a given material to adopt multiple crystalline packing states, is a powerful approach for investigating how changes in molecular packing influence charge transport within organic semiconductors. In this study, a new “thin film” polymorph of the high-performance, p-type small molecule N-octyldiisopropylsilyl acetylene bistetracene (BT) is isolated and characterized. Structural changes in the BT films are monitored using static and in situ grazing-incidence X-ray diffraction. The diffraction data, combined with simulation and crystallographic refinement calculations, show the molecular packing of the “thin film” polymorph transforms from a slipped 1D π-stacking motif to a highly oriented and crystalline film upon solvent vapor annealing with a 2D brick-layer π-stacking arrangement, similar to the so-called “bulk” structure observed in single crystals. Charge transport is characterized as a function of vapor annealing, grain orientation, and temperature. Demonstrating that mobility increases by three orders of magnitude upon solvent vapor annealing and displays a differing temperature-dependent mobility behavior.
|Original language||English (US)|
|Journal||Advanced Materials Interfaces|
|State||Published - May 9 2018|
Bibliographical noteFunding Information:
E.K.B., J.L., and A.L.B. acknowledge the National Science Foundation (DMR-1508627) for support of this work. This work is based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS), which is supported by the National Science Foundation under Award No. DMR-1332208.
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- organic semiconductors
- solvent vapor annealing
ASJC Scopus subject areas
- Mechanics of Materials
- Mechanical Engineering