Spherulitic growth under solvent-vapor annealing: theory and experiments on thin-film blends of organic small-molecule semiconductors
Saturday, October 24, 2015 - 9:45am - 10:25am
Doping spun-cast films of organic semiconductors with additive and then inducing spherulitic crystallization by solvent-vapor annealing offers a promising means for controlling grain size of the semiconductor films. During solvent-vapor annealing, large-scale crystallization takes place and neighboring spherulites grow until they impinge. The growth rate, as measured by the normal velocity of the propagating boundary of the spherulite, is constant for a given temperature, solvent-vapor pressure, initial additive mole fraction, and substrate. Based on a theory which assumes that no diffusion of any species takes place, we derive formulas which show how the mole fraction of the additive affects spherulitic growth rates in such films when the semiconductor and the additive remain in solution within the spherulitic phase and when they become segregated there. Measurements of spherulitic growth rates were made on triethylsilylethynyl anthradithiophene (TES ADT) films blended with various additives. The experimental results are compared with the theoretical predictions. This talk presents joint work with M.E. Jabbour, R. Paroni, Y.-L. Loo, A.K. Hailey, S.S. Lee, J.E. Anthony, and M.A. Grimminger.