Towards understanding the behavior of indigo thin films in organic field-effect transistors: a template effect of the aliphatic hydrocarbon dielectric on the crystal structure and electrical performance of the semiconductor

Abstract

Here we report a systematic investigation of indigo thin films grown on different dielectric underlayers. It has been revealed that aliphatic hydrocarbon chains serve as templates inducing the formation of a new crystal modification of indigo which possesses advanced charge transport properties and affords a dramatic improvement in the electrical performance of organic field-effect transistors.

Design of indigo derivatives as environment-friendly organic semiconductors for sustainable organic electronics

“…Thus, the tetrafluorindigo 9 behaves similarly to the parent indigo while undergoing epitaxial growth on aliphatic hydrocarbons. 11 However, in contrast to the parent indigo, two different crystal modifications of 9 formed on TC and BCB dielectrics showed very similar performances in OFETs (Table 2). We note that tilting of molecules in the stack might affect significantly lateral charge transport required for efficient OFET operation.…”

“…11 It is possible that similar effects also play a role in the case of indigoids 1-9. To verify this hypothesis, one has to compare the real 3D crystal structures of indigoids (bulk structures) with the structures of polymorphs formed in thin films at the semiconductor/dielectric interface (surface structures).…”

“…We have shown recently that electrical performance of pristine indigo can be enhanced using a strong template effect of aliphatic hydrocarbon dielectrics. 11 In the present work we explored a potential of chemical derivatization of indigo as a route for designing indigoid-based semiconductors with advanced properties. Nine different indigo derivatives were synthesized and investigated in order to identify fundamental correlations between the molecular structures of compounds, their crystal packing, film morphology, optical, electrochemical and electrical properties as well as operational stability under ambient conditions.…”

Dibenzoindigo: A Nature‐Inspired Biocompatible Semiconductor Material for Sustainable Organic Electronics

“…Such behavior suggests the formation of H‐aggregates, which are characterized by a much smaller displacement of the molecules in the stack resulting in enhanced charge transport properties of the material …”

An iodine effect in ambipolar organic field-effect transistors based on indigo derivatives

“…5e shows X-ray diffraction (XRD) peaks. 35 Without assuming the thin-film structure different from the crystal structure, we have to attribute the high performance of 4 to the anomalous iodine-iodine electronic interaction coming from t X-X, HOMO . 34 The 2θ value coming from the indigo derivatives decreases systematically from 1 to 4, and the corresponding d-value increases as shown in Table 2.…”