Dipole-Oriented Molecular Solids Can Undergo a Phase Change and Still Maintain Electrical Polarization

Andrew Cassidy*, Mads R. V. Jørgensen, Alexander Rosu-Finsen, Jerome Lasne, Jakob H. Jørgensen, Artur Glavic, Valeria Lauter, Bo B. Iversen, Martin R. S. McCoustra, David Field

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)
55 Downloads (Pure)


It has recently been demonstrated that nanoscale molecular films can spontaneously assemble to self-generate intrinsic electric fields that can exceed 108 V/m. These electric fields originate from polarization charges in the material that arise because the films self-assemble to orient molecular dipole moments. This has been called the spontelectric effect. Such growth of spontaneously polarized layers of molecular solids has implications for our understanding of how intermolecular interactions dictate the structure of molecular materials used in a range of applications, for example, molecular semiconductors, sensors, and catalysts. Here we present the first in situ structural characterization of a representative spontelectric solid, nitrous oxide. Infrared spectroscopy, temperature-programmed desorption, and neutron reflectivity measurements demonstrate that polarized films of nitrous oxide undergo a structural phase transformation upon heating above 48 K. A mean-field model can be used to describe quantitatively the magnitude of the spontaneously generated field as a function of film-growth temperature, and this model also recreates the phase change. This reinforces the spontelectric model as a means of describing long-range dipole-dipole interactions and points to a new type of ordering in molecular thin films.

Original languageEnglish
Pages (from-to)24130-24136
Number of pages7
JournalJournal of Physical Chemistry C
Issue number42
Early online date2 Oct 2016
Publication statusPublished - 27 Oct 2016

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry


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