On the Largest Possible Mobility of Molecular Semiconductors and How to Achieve It

A large database of known molecular semiconductors is used to define a plausible physical limit to the charge carrier mobility achievable within this materials class. From a detailed study of the desirable properties in a large dataset, it is possible to establish whether such properties can be optimized independently and what would be a reasonably achievable optimum for each of them. All relevant parameters are computed from a set of almost five thousand known molecular semiconductors, finding that the best known materials are not ideal with respect to all properties. These parameters in decreasing order of importance are the molecular area, the nonlocal electron–phonon coupling, the 2D nature of transport, the local electron–phonon coupling, and the highest transfer integral. It is also found that the key properties related to the charge transport are either uncorrelated or “constructively” correlated (i.e., they improve together) concluding that a tenfold increase in mobility is within reach in a statistical sense, on the basis of the available data. It is demonstrated that high throughput screenings, when coupled with physical models of transport produce both specific target materials and a more general physical understanding of the materials space.