posted on 2022-01-05, 23:07authored byArie van der Lee, Maurizio Polentarutti, Gilles H. Roche, Olivier J. Dautel, Guillaume Wantz, Frédéric Castet, Luca Muccioli
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.