Strategies to reduce the dynamic disorder in molecular semiconductors

Abstract

The dynamic disorder is known to be one of the crucial parameters limiting the charge carrier transport in molecular semiconductors and a parameter that cannot be easily controlled through known design rules. To identify much needed guiding principles we evaluate the dependence of dynamic disorder on a large number of molecular and crystal characteristics for a set of almost five thousand known molecular semiconductors. We find that the strength of dynamic disorder is highly correlated with the gradient of the transfer integral, a property easily computable for any molecular orientation. We also show that orientations of molecular pairs with just a few atoms in contact are more likely to yield low dynamic disorder. This observation is highly counterintuitive as for years the focus has been to maximize the number of π-stacked atoms. Other properties with meaningful influence on the dynamic disorder include the presence of alkyl chains, the strength of the transfer integral and the presence of heavy atoms. The findings of this work provide important design principles for low-disorder high-mobility molecular semiconductors.