Abstract
Highly crystalline thin films in organic semiconductors are important for applications in high-performance organic optoelectronics. Here, the effect of grain boundaries on the Hall effect and charge transport properties of organic transistors based on two exemplary benchmark systems is elucidated: (1) solution-processed blends of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) small molecule and indacenodithiophene-benzothiadiazole (C16IDT-BT) conjugated polymer, and (2) large-area vacuum evaporated polycrystalline thin films of rubrene (C42H28). It is discovered that, despite the high field-effect mobilities of up to 6 cm2 V−1 s−1 and the evidence of a delocalized band-like charge transport, the Hall effect in polycrystalline organic transistors is systematically and significantly underdeveloped, with the carrier coherence factor α < 1 (i.e., yields an underestimated Hall mobility and an overestimated carrier density). A model based on capacitively charged grain boundaries explaining this unusual behavior is described. This work significantly advances the understanding of magneto-transport properties of organic semiconductor thin films.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1903617 |
| Journal | Advanced Functional Materials |
| DOIs | |
| State | Published - Jul 11 2019 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: The authors are grateful to the following programs for the financial support of this work. V.P. and H.H.C. acknowledge support from the National Science Foundation under the grant ECCS-1806363 and the Rutgers Energy Institute (REI). K.C. and H.H.C. acknowledge support from the Center for Advanced Soft-Electronics at Pohang University of Science and Technology funded by the Republic of Korea's Ministry of Science, ICT and Future Planning as Global Frontier Project (CASE-2011-0031628). M.A.F. and B.P.R. acknowledge support from the National Science Foundation Award No. ECCS-1709222. A.F.P., J.P., M.H., and T.D.A. acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) (Grant No. EP/G037515/1) and from the European Research Council (ERC) AMPRO Project No. 280221. T.D.A. and A.F.P. acknowledge the support from King Abdullah University of Science and Technology (KAUST). O.S. acknowledge the support of the Center for Absorption in Science of the Ministry of Immigrant Absorption in Israel under the framework of the KAMEA Program.