Mobility anisotropy in the herringbone structure of asymmetric Ph-BTBT-10 in solution sheared thin film transistors

Thin films of the organic semiconductor Ph-BTBT-10 and blends of this material with polystyrene have been deposited by a solution shearing technique at low (1 mm s−1) and high (10 mm s−1) coating velocities and implemented in organic field-effect transistors. Combined X-ray diffraction and electrical characterisation studies prove that the films coated at low speed are significantly anisotropic. The highest mobility is found along the coating direction, which corresponds to the crystallographic a-axis. In contrast, at high coating speed the films are crystallographically less ordered but with better thin film homogeneity and exhibit isotropic electrical characteristics. Best mobilities are found in films prepared at high coating speeds with the blended semiconductor. This work demonstrates the interplay between the crystal packing and thin film morphology and uniformity and their impact on the device performance.The authors also thank the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 811284 (UHMob), the Spanish Ministry project GENESIS PID2019-111682RB-I00, the “Severo Ochoa” Programme for Centers of Excellence in R&D (FUNFUTURE, CEX2019-000917-S), the Generalitat de Catalunya (2017-SGR-918) and the Austrian Science Fund (FWF): [P30222]. A. T. thanks his enrolment in the Materials Science PhD program of Universitat Autònoma de Barcelona and acknowledges FPU fellowship from the Spanish Ministry. We thank the synchrotron Elettra, Trieste for provision of synchrotron radiation and Luisa Barba for her support to use the beamline XRD1. G.S. acknowledges postdoctoral fellowship support from the Belgian National Fund for Scientific Research (FNRS). We acknowledge support of the publication fee from the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe