Structural stability of naphthyl end-capped oligothiophenes in organic field-effect transistors measured by grazing-incidence X-ray diffraction in operando

Abstract

. (2017) Structural stability of naphthyl end-capped oligothiophenes in organic field-effect transistors measured by grazingincidence X-ray diffraction in operando. Organic Electronics. Permanent WRAP URL:http://wrap.warwick.ac.uk/89989 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. AbstractWe report on microstructural durability of 5,5'-bis(naphth-2-yl)-2,2'-bithiophene (NaT2) in organic field effect transistors (OFETs) in operando monitored by grazing-incidence X-ray diffraction (GIXRD). NaT2 maintains its monoclinic bulk motif in operating OFETs with a = 20.31 ± 0.06Å, b = 6.00 ± 0.01Å, c = 8.17 ± 0.04Å and β = (96.64 ± 0.74)• . Crystallites appear as a mosaic of single crystals reaching through the whole 50 nm thick active layer. The lattice parameters variation (<1%) falls within the statistical error of structure refinement when the OFET gate voltage is varied from 0 V to -40 V; or when the OFET is continuously cycled within this voltage interval over more than 10 h period. Within the first few cycles, both the hole mobility and threshold voltage are changing but then reach stable levels with an average mobility of (3.25 ± 0.04) × 10 −4 cm 2 /Vs and an average threshold voltage of −13.6 ± 0.2 V, both varying less than 4% for the remainder of the 10 h period. This demonstrates crystalline stability of NaT2 in operating OFETs.

Structural basis for a naphthyl end-capped oligothiophene with embedded metallic nanoparticles for organic field-effect transistors

“…The smearing of the Bragg peaks along q z suggests that NaT3 exhibits a higher degree of disorder along the stacking direction perpendicular to the surface normal compared with the closely related but symmetrical 5,5 0 -bis(naphth-2-yl)-2,2 0 -bithiophene (NaT2), which shows equally resolved Bragg peaks (rather than rods) in both directions. 7 Yet the pattern has a prominent similarity to what is reported for 5-decyl-5 00 -(naphthalen-2-yl)-2,2 0 :5 0 ,2 00 -terthiophene (D3TN) in Ref. 23, which likewise contains three thiophene rings with one end-group replaced by an alkyl-group.…”

“…5,6 Of particular interest are thiophene-based oligomers because of their hole transport properties and stable device performance under atmospheric conditions. [7][8][9] By end-capping the thiophene rings with aryl groups, the polymerization potential is hindered and intermolecular packing is promoted. 9 We have recently shown that the photoresponsivity in naphthyl end-capped oligothiophene based OPTs can be enhanced by utilizing the plasmonic properties of embedded metallic nanoparticles.…”

Surface-Controlled Crystal Alignment of Naphthyl End-Capped Oligothiophene on Graphene: Thin-Film Growth Studied by in Situ X-ray Diffraction

“…We have recently started to focus on the most symmetric variant of these materials, 5,5´-bis(naphth-2-yl)-2,2´-bithiophene (NaT2, Scheme 1), and investigated the relation between structure and OFET environment, and confirmed the stability hypotheses of Geng and co-workers by X-ray investigations of NAT2 OFETs in operando. 20 At the same time, Balzer et al 21 have found how NaT2 forms an extraordinary fiber-like surface morphology on muscovite mica, presumably originating from the anisotropy of the muscovite surface. These findings make NaT2 an intriguing new candidate when turning to the fundamentals of surface controlled crystal growth.…”

Modeling of Grazing-Incidence X-ray Diffraction from Naphthyl End-Capped Oligothiophenes in Organic Field-Effect Transistors

“…previously. [13][14][15] NaT2 and NaT3 have many similarities. Phenomenologically, these films exhibit a plate like crystal habit when grown on SiO 2 .…”