Discovering Crystal Forms of the Novel Molecular Semiconductor OEG-BTBT

Priya Pandey, Nicola Demitri, Lara Gigli, Ann Maria James, Félix Devaux, Yves Henri Geerts, Enrico Modena*, Lucia Maini

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This work is focused on a polymorphic and crystallographic study of a novel p-type organic semiconductor 2,7-bis(2-(2-methoxyethoxy)ethoxy)benzo[b]benzo[4,5]thieno[2,3-d]thiophene (OEG-BTBT). The well-known BTBT core is functionalized by eight-atom-long oligoethylene glycol side chains. Our results demonstrate the discovery of three crystal forms of the OEG-BTBT molecule, namely, Form I, Form II, and Form III, in different experimental conditions. Crystal structures of Form I and Form III are reported, while only unit cell indexing of Form II could be determined. Form I and Form II are enantiotropically related, and Form II is stable at temperatures higher than 127 °C. The kinetics of transformation to Form II was studied by the Avrami equation. Form III is a solvate crystal form which is rarely observed in the field of organic electronics, and upon release of dichloromethane, it converts to Form I. Furthermore, we studied the mechanical properties of the Form I crystals, which exhibit plastic bending upon applying mechanical stress in the [100] direction. This distinct mechanical behavior is rationalized by the slip layer topology, the intermolecular interactions energies from energy frameworks, and the Hirshfeld surface analysis.

Original languageEnglish
Pages (from-to)1680-1690
Number of pages11
JournalCrystal Growth and Design
Volume22
Issue number3
DOIs
Publication statusPublished - 2 Mar 2022

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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