Impact of 2‐Ethylhexyl Stereoisomers on the Electrical Performance of Single‐Crystal Field‐Effect Transistors. Issue 44 (14th September 2018)

• Record Type: Journal Article
• Authors: He, Tao; Leowanawat, Pawaret; Burschka, Christian; Stepanenko, Vladimir; Stolte, Matthias; Würthner, Frank
• Is Part Of: Advanced materials. Volume 30:Issue 44(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-09-14
• Subjects: chirality -- diketopyrrolopyrroles -- organic electronics -- single‐crystal field‐effect transistors; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201804032
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Many organic semiconductors (OSCs) inherit chiral alkyl chains, which ensure the desirable high solubility for solution‐processing but may also lead to disorder, inhomogeneous film‐formation, as well as interfacial defects due to the presence of mixtures of stereoisomers or diastereomers, which impair their peak performance. Here, single‐crystal field‐effect transistors (SCFETs) of a diketopyrrolopyrrole‐based organic semiconductor with chiral 2‐ethylhexyl substituents by sublimation in air and organic ribbon mask method are fabricated. Devices of the mesomer ( R / S ), both enantiomers ( R / R, S / S ), as well as mixtures of these three stereoisomers measured under ambient conditions exhibit all appreciable p‐channel charge carrier mobilities of > 0.1 cm 2 V −1 s −1 despite different packing arrangement in the R / S, R / R (or S / S ), and racemate crystal structures. These results suggest a surprising tolerance for isomeric impurities. The highest literature‐reported p‐channel mobility so far for a diketopyrrolopyrrole‐based OSC of 3.4 cm 2 V −1 s −1 ( I on / I off of 1 × 10 6 ) is, however, only obtained for the pure R / S mesomer, illustrating the inherent potential of stereochemical purity. These results on SCFETs are further substantiated by studies on organic thin‐film transistors (OTFTs) of pure and mixed thin films of the different stereoisomers. Abstract : Single‐crystal field‐effect transistors of three stereoisomers of a chiral diketopyrrolopyrrole‐based organic semiconductor and mixtures thereof are fabricated by sublimation in air, which yield p‐channel charge carrier mobilities as high as 3.4 cm 2 V −1 s −1 . Distinct differences in hole transport are related to the individual single‐crystal structures and enable their impact on the performance on mixed thin films to be assessed.