Addition of the Lewis Acid Zn(C6F5)2 Enables Organic Transistors with a Maximum Hole Mobility in Excess of 20 cm2/Vs

Abstract
Incorporating the molecular organic Lewis acid tris(pentafluorophenyl)borane [B(C6 F5 )3 ] into organic semiconductors has shown remarkable promise in recent years for controlling the operating characteristics and performance of various opto/electronic devices, including, light-emitting diodes, solar cells, and organic thin-film transistors (OTFTs). Despite the demonstrated potential, however, to date most of the work has been limited to B(C6 F5 )3 with the latter serving as the prototypical air-stable molecular Lewis acid system. Herein, the use of bis(pentafluorophenyl)zinc [Zn(C6 F5 )2 ] is reported as an alternative Lewis acid additive in high-hole-mobility OTFTs based on small-molecule:polymer blends comprising 2,7-dioctyl[1]benzothieno [3,2-b][1]benzothiophene and indacenodithiophene-benzothiadiazole. Systematic analysis of the materials and device characteristics supports the hypothesis that Zn(C6 F5 )2 acts simultaneously as a p-dopant and a microstructure modifier. It is proposed that it is the combination of these synergistic effects that leads to OTFTs with a maximum hole mobility value of 21.5 cm2 V-1 s-1 . The work not only highlights Zn(C6 F5 )2 as a promising new additive for next-generation optoelectronic devices, but also opens up new avenues in the search for high-mobility organic semiconductors.

Citation
Paterson AF, Tsetseris L, Li R, Basu A, Faber H, et al. (2019) Addition of the Lewis Acid Zn(C6F5)2 Enables Organic Transistors with a Maximum Hole Mobility in Excess of 20 cm2/Vs. Advanced Materials: 1900871. Available: http://dx.doi.org/10.1002/adma.201900871.

Acknowledgements
T.D.A., A.F.P., A.B., H.F., and M.R.N. acknowledge the King Abdullah University of Science and Technology (KAUST) for financial support. R.L. used CMS beamline of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract No. DE-SC0012704. L.T. acknowledges support for the computational time granted from GRNET in the National HPC facility—ARIS—under project STEM. M.H. and J.P. thank EPRSC (EP/L016702/1) and the Royal Society for their support.

Publisher
Wiley

Journal
Advanced Materials

DOI
10.1002/adma.201900871

Additional Links
https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201900871

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