The effect of pressure on the intermolecular vibrational modes in high charge carrier mobility molecular semiconductors

The van der Waals nature of organic semiconductors (OSCs) offers low cost processing while intermolecular vibrations affect their charge transport properties. By using inelastic neutron scattering and terahertz spectroscopy, combined with quantum mechanical simulations, we have characterized for the first time the full-spectrum of low-frequency motions in several OSCs, identifying the long axis sliding motion as the killer phonon mode. Within this framework, the aim of this proposal is to push our study further and investigate the impact of pressure on the vibrational spectrum present in these soft materials. This will allow us to 1) understand the impact of pressure on the thermal disorder in OSCs, 2) how the long axis sliding motion is hampered as a function of molecular design and packing and 3) develop potential pressure/strain strategies to improve transport properties.