Issue 20, 2022

Thorough investigation on the high-temperature polymorphism of dipentyl-perylenediimide: thermal expansion vs. polymorphic transition

Abstract

N,N′-Dipentyl-3,4,9,10-perylendiimide (PDI-C5) is an organic semiconducting material which has been extensively investigated as model compound for its optoelectronic properties. It is known to be highly thermally stable, that it exhibits solid-state transitions with temperature and that thermal treatments lead to an improvement in its performance in devices. Here we report a full thermal characterization of PDI-C5 by combination of differential scanning calorimetry, variable temperature X-ray diffraction, hot stage microscopy, and variable temperature Raman spectroscopy. We identified two high temperature polymorphs, form II and form III, which form respectively at 112 °C and at 221 °C and we determined their crystal structure from powder data. Form II is completely reversible upon cooling with low hysteresis, while form III revealed a different thermal behaviour upon cooling depending on the technique and crystal size. The crystal structure features of the different polymorphs are discussed and compared, and we looked into the role of the perylene core and alkyl chains during solid-state transitions. The thermal expansion principal axis of PDI-C5 crystal forms is reported showing that all the reported forms possess negative thermal expansion (X1) and large positive thermal expansion (X3) which are correlated to thermal behaviour observed.

Graphical abstract: Thorough investigation on the high-temperature polymorphism of dipentyl-perylenediimide: thermal expansion vs. polymorphic transition

Supplementary files

Article information

Article type
Paper
Submitted
28 Dec 2021
Accepted
29 Apr 2022
First published
03 May 2022
This article is Open Access
Creative Commons BY license

J. Mater. Chem. C, 2022,10, 8089-8100

Thorough investigation on the high-temperature polymorphism of dipentyl-perylenediimide: thermal expansion vs. polymorphic transition

F. Marin, S. Tombolesi, T. Salzillo, O. Yaffe and L. Maini, J. Mater. Chem. C, 2022, 10, 8089 DOI: 10.1039/D1TC06132A

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