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Magnetic Properties of Quinoidal Oligothiophenes: More Than Good Candidates for Ambipolar Organic Semiconductors?
Author(s) -
Ponce Ortiz R.,
Casado J.,
Hernández V.,
López Navarrete J. T.,
Ortí E.,
Viruela P. M.,
Milián B.,
Hotta S.,
Zotti G.,
Zecchin S.,
Vercelli B.
Publication year - 2006
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200500404
Subject(s) - ambipolar diffusion , materials science , raman spectroscopy , electron paramagnetic resonance , organic semiconductor , chemical physics , semiconductor , photochemistry , electron , nuclear magnetic resonance , optoelectronics , chemistry , optics , physics , quantum mechanics
A series of quinoidal oligothiophenes have been investigated by means of solid‐state Fourier‐transform (FT)‐Raman and electron spin resonance (ESR) spectroscopies complemented with density functional theory calculations. FT‐Raman spectra recorded as a function of temperature show that, upon laser irradiation, the molecules undergo a reversible structural evolution from a quinoid‐type pattern at low temperature to an aromatic‐type pattern at high temperature. Moreover, ESR spectra show that a portion of these compounds exists in a biradical state at room temperature. These seemingly disconnected findings and others, such as conformational isomerism, are consistently explained by the consideration of biradical species associated with the presence of low‐lying triplet electronic states. In addition to the well‐established versatility of quinoidal oligothiophenes regarding ambipolar electrical actuation in field‐effect transistors, the exhibition of dual electrical and magnetic behavior leads to the prospect of new materials that have tunable electrical, optical, and magnetic properties.