The charge mobility of organic semiconductors are accurately predicted using first principles simulations validated by inelastic neutron scattering experiments.

Understanding the nature of dopant dynamics in the solid state is critical for improving the longevity and stability of organic electronic devices and for optimizing the dopinginduced solubility control (DISC) patterning method. In this work, we use quasi-elastic neutron scattering (QENS) and fluorescence quenching techniques to develop a comprehensive picture of both the microscopic and macroscopic dynamics of the soluble p-type molecular dopant tetrafluoromethyloxycarbonyltricyanoquinodimethane (F4MCTCNQ) in the conductive polymer poly(3-hexylthiophene-2,5-diyl) (P3HT). Specifically, fast dynamics (ps−ns) of the dopant, such as the methyl and the methoxycarbonyl group rotations, are observed in QENS experiments. From confocal fluorescence microscope experiments, longer-range/slower dopant diffusion (ms−days) iscaptured. However, in order to fit these data, it is necessary to incorporate a Langmuir isotherm equilibrium between the neutral and ionized dopant molecules. Ionized F4MCTCNQ is strongly favored by the equilibrium, but it diffuses 3 orders of magnitude slower than neutral species. Moreover, the macroscopic diffusion is found to depend mostly on the minority concentration of neutral dopant molecules in the film. Finally, the global diffusion coefficient of the monoester-substituted dopant F4MCTCNQ is shown to be more than 1 order of magnitude smaller than that of the widely used dopant F4TCNQ. 49 solution processes to achieve micrometer and submicrometer 50 resolution, respectively, in a method that is compatible with 51 roll-to-roll solution processing. 13,16 For DISC patterning, the 52 lateral diffusion of the dopant limits the ultimate resolution of 53 the pattern. Therefore, for both the stability of completed 54 organic devices and for fabrication of these devices using 55 solution compatible methods, understanding the dynamics of 56 the dopants is extremely important to further application 57 development. 58 The measurement of small molecular dopant diffusion is 59 particularly challenging because dopants are present in trace 60 quantities and composed of the same light elements (C, H, O, 61 N, S) as the host OSCs. Most of these studies so far have