Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

Abstract

We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply band-like transport.

References in corpus (5)

• Density of bulk trap states in organic semiconductor crystals: discrete levels induced by oxygen in rubrene
• Quantum coherence and carriers mobility in organic semiconductors
• Thermal Narrowing of the Electronic Bandwidths in Organic Molecular Semiconductors: Impact of the Crystal Thermal Expansion
• On the Munn-Silbey approach to polaron transport with off-diagonal coupling
• Electron-phonon coupling in crystalline organic semiconductors: Microscopic evidence for nonpolaronic charge carriers