- Tytuł:
- Physics of Neutral-to-Ionic Phase Transition in Organic Charge Transfer Semiconducting Compounds
- Autorzy:
-
Cailleau, H.
Lemée-Cailleau, M. H.
Le Cointe, M.
Luty, T. - Powiązania:
- https://bibliotekanauki.pl/articles/1967953.pdf
- Data publikacji:
- 1997-10
- Wydawca:
- Polska Akademia Nauk. Instytut Fizyki PAN
- Tematy:
-
71.38.+i
61.50.Ks
71.35.Aa - Opis:
- An uncommon excitonic instability takes place in some exotic semiconducting compounds. Indeed, the equilibrium neutral-to-ionic (N-I) phase transition, as well as the non-equilibrium photo-induced phase transformation, observed in some organic charge-transfer complexes, originate from intra- and inter-chain cooperative effects between structurally relaxed charge-transfer excitations. This electronic-structural phase transition manifests itself by a change of the degree of charge-transfer and a dimerization distortion with the formation of donor-acceptor pairs along the stacking axis in the I phase. Thermal charge-transfer excitations associated with the formation of I strings along N chains are at the heart of the mechanism of this phase transition. These relaxed electronic excitations, which are an intrinsic feature of low-dimensional systems with strong electron-phonon coupling, can be described in terms of self-trapping and self-multiplication of charge-transfer excitons. Precise structural studies on the prototype compound, tetrathiafulvalene-p-chloranil allow to highlight the respective role taken by the ionicity and the dimerization. Symmetry and thermodynamics analysis of the N-I transition, based on recent determination of the pressure-temperature phase diagram, make possible to present a consistent picture of this phase transition. Supported by theoretical considerations taking into account the interplay between quantum and thermal effects, the experimental observations show that the N-I transition results from the condensation and the ordering (crystallization) of charge-transfer excitations, following a phase diagram analogous to the solid-liquid-gas one.
- Źródło:
-
Acta Physica Polonica A; 1997, 92, 4; 597-608
0587-4246
1898-794X - Pojawia się w:
- Acta Physica Polonica A
- Dostawca treści:
- Biblioteka Nauki
Artykuł