Abstract: Terahertz rotational dynamics and their influence on material properties: from semiconductors to energy storage

The low-frequency vibrational dynamics of materials are critically important to a vast-array of material properties, ranging from thermal expansion to electron-phonon coupling in semiconductors. Molecular solids, in particular, exhibit a rich set of terahertz dynamics, with associated complex and large-amplitude vibrational mode types that are highly-excited at ambient conditions. While much focus over the last several decades of terahertz spectroscopy has focused on accurately assigning terahertz spectra, technological advances have made this fairly straightforward, and over the last several years focus has shifted towards actually leveraging the molecular motions themselves to understand bulk material functions. In this work, the varied nature of terahertz dynamics will be discussed in materials ranging from organic electronics to pharmaceutical solids, and their role in dictating material properties will be highlighted. In particular, such dynamics are directly related to the low-charge carrier mobilities in organic semiconductors, while also being responsible for numerous phase transformation processes in thermal storage crystals. Thus, an in-depth understanding of such phenomena is crucial to designing next-generation materials for advanced applications, which will be further discussed.