Molecular vibrations play a critical role in the charge transport properties of weakly van der Waals bonded organic semiconductors. To understand which specific phonon modes contribute most strongly to the electron–phonon coupling and ensuing thermal energetic disorder in some of the most widely studied high‐mobility molecular semiconductors, state‐of‐the‐art quantum mechanical simulations of the vibrational modes and the ensuing electron–phonon coupling constants are combined with experimental measurements of the low‐frequency vibrations using inelastic neutron scattering and terahertz time‐domain spectroscopy. In this way, the long‐axis sliding motion is identified as a “killer” phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high‐mobility molecular semiconductors is suggested.

The present work reports a novel modification methodology for halloysite nanotubes (HNTs) that includes two successive steps, i.e., activation by piranha solution and silanization reaction. A commercial silane coupling agent, 3-aminopropyltriethoxysilane (APS), was selected to modify the surface of HNTs. The presence of APS moieties on the HNT surface was characterized by the combination of Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen sorption. For the coupling reaction, the effect of reaction time, temperature, rehydration and APS concentration on the course of silanization degree was carefully investigated. The mechanism and the grafted product structure of the reaction between activated HNTs and APS were revealed through ²⁹Si solid-state NMR spectroscopy and XPS analysis. The result shows that piranha solution is an effective activation agent for silanization of HNTs. A higher reaction temperature (120 °C) contributed to a higher grafted amount compared with a lower temperature (70 °C). Moisture led to a higher degree of silanization. The grafted amount increased with APS concentration and leveled off at about 1%. Further increase in the APS concentration only led to a drastic decrease in grafting yield. The grafting reaction was confirmed by the presence of tridentate (T³) and bidentate (T²) bonded Si in ²⁹Si NMR. Free terminal amino groups and protonated amine groups were identified in modified HNTs by XPS.