Towards Novel Organic Electronics: Integrating Simulation and Neutron Scattering*

Organic semiconductors are a promising class of materials due to the possibility of creating low-cost, flexible materials that have applications in photovoltaic, LED, and transistor technologies. However, current state-of-the-art organic semiconductors still have lower electrical/hole mobilities than the best inorganic semiconductors because of low energy vibrations present in organic semiconductors due to the loosely-bound nature of molecular solids. These vibrations reduce the hole mobility of the material by scattering free charge carriers, causing a localization of the charge states. We demonstrate that we can identify the vibrational modes for six different organic semiconductors using DFT simulations verified by neutron vibrational spectroscopy results. We use the simulated vibrational modes to find theoretical values of hole mobility for the materials, which demonstrates how variation in the chemical structure affects functional properties. Our work provides valuable information for the creation of the next-generation of organic semiconductors that reduce the vibrational disorder that localizes charge carriers.