Phonon dispersion of the organic semiconductor rubrene

The phonon dispersion of the organic semiconductor, rubrene, is experimentally measured by the inelastic x-ray scattering experiments performed at room temperature. In organic crystals, weak van der Waals interaction among the molecules increases the amplitude of the lattice vibration. Therefore, phonons are essential in organic crystals. However, there are few experimental reports on phonon dispersion in organic semiconductors and no reports on modern high-mobility organic semiconductors, which hampers the complete understanding of many phenomena in organic semiconductors. The dispersion of low-energy optical and acoustic phonon modes, including both intermolecular and intramolecular modes, is measured along the orthorhombic principal axes. Short-wavelength modes are expected to be affected by the anisotropic molecular shape, and the experimental result suggests that even the phonons having a wavelength of 140 ?? are well modified, showing strong mixing of local and nonlocal phonon modes. This study provides a robust foundation for investigating organic semiconductors and understanding the lattice dynamics of highly anisotropic motifs.

Automated summary

The phonon dispersion of the organic semiconductor rubrene is experimentally measured by inelastic X-ray scattering experiments at room temperature. The results show that phonons are essential in organic crystals. However, there are few experimental reports on phonon dispersion in organic semiconductors. This study provides an important foundation for further investigation of organic semiconductors and understanding the lattice dynamics of highly anisotropic motifs.