Dynamic Disorder Design Rules for Small-Molecule Organic Semiconductors

Small-molecule organic semiconductors are promising materials for applications ranging from solar cells to medical sensors. Their nearly infinite design space means that, in theory, it is possible to tailor the material to the exact specifications of a particular application. In reality, however, design rules to improve mobility (µ) remain elusive because of the complex calculations required to understand its limiters. Transient localization theory posits that charge carriers are slowed down by the collective phonon motions, called dynamic disorder, which localize charge carriers temporarily. Here, we present a streamlined simulation workflow that simplifies simulation of dynamic disorder and enables engineering of new molecular structures based on phonon dynamics. We combine this workflow with a novel visualization technique that enables per-atom insights into how µ is limited. We apply this workflow and analysis to a series of -acenes and a series of BTBT-based molecules. Then we identify design rules in each series that identify possible ways to improve the µ beyond current experimental limits using phonon engineering.