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Published on: October 31, 2019
Temperature-Dependent Structural Phase Transition in Rubrene Single Crystals: The Missing Piece from the Charge
Arie van der Lee1, Maurizio Polentarutti2, Gilles H Roche3,4
1IEM, Université de Montpellier, CNRS, ENSCM, 34095 Montpellier, France.
Abstract:
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.
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