Structural Organization of π Conjugated Highly Luminescent Molecular Material

B. Toudic (1) , P. Limelette (1) , G. Froyer (2) , F. Le Gac (1) , A. Moréac (1) , P. Rabiller (3)

1 GMCM - Groupe matière condensée et matériaux
2 IMN - Institut des Matériaux Jean Rouxel
3 IPR - Institut de Physique de Rennes

We report on striking evidence for a room temperature structural phase instability in p-hexaphenyl, inducing a nonplanar conformation of the molecules. Solid state proton NMR and single crystal x-ray diffraction allow the analysis of the organization, the individual dynamics and the involved symmetry breaking. The analysis of Raman spectra above and below room temperature reveals a singular behavior suggesting a modification of the overlap between the electronic wave function induced by the non-planarity. These results provide a new basis to answer fundamental issues related to molecular and electronic materials and, in particular, luminescent organic devices.

Domains: Physics [physics]; Condensed Matter [cond-mat]; Materials Science [cond-mat.mtrl-sci]

B. Toudic, P. Limelette, G. Froyer, F. Le Gac, A. Moréac, et al.. Structural Organization of π Conjugated Highly Luminescent Molecular Material. Physical Review Letters, 2005, 95 (21), pp.215502. ⟨10.1103/PhysRevLett.95.215502⟩. ⟨hal-01870053⟩