Temperature-Dependent Structural Phase Transition in Rubrene Single Crystals: The Missing Piece from the Charge Mobility Puzzle?

• Published in: The journal of physical chemistry letters Vol. 13; no. 1; pp. 406 - 411
• Main Authors: van der Lee, Arie, Polentarutti, Maurizio, Roche, Gilles H, Dautel, Olivier J, Wantz, Guillaume, Castet, Frédéric, Muccioli, Luca
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.01.2022
• Subjects: Chemical Sciences; Cristallography; Organic chemistry; Physical Insights into Materials and Molecular Properties
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.1c03221

Accurate structural models for rubrene, the benchmark organic semiconductor, derived from synchrotron X-ray data in the temperature range of 100–300 K, show that its cofacially stacked tetracene backbone units remain blocked with respect to each other upon cooling to 200 K and start to slip below that temperature. The release of the blocked slippage occurs at approximately the same temperature as the hole mobility crossover. The blocking between 200 and 300 K is caused by a negative correlation between the relatively small thermal expansion along the crystallographic b-axis and the relatively large widening of the angle between herringbone-stacked tetracene units. DFT calculations reveal that this blocked slippage is accompanied by a discontinuity in the variation with temperature of the electronic couplings associated with hole transport between cofacially stacked tetracene backbones.