A high-voltage rectangular pulse was applied to the electro-spray deposition (ESD) to control the evaporation-induced self-assembly of poly(3-hexylthiophene-2,5-diyl) (P3HT). Two groups of P3HT thin films were deposited by a series of high-voltage rectangular pulses. Compared with the ESD driven by a constant voltage, the pulse-driven ESD enables to probe the effect of solvent evaporation on the self-assembly of P3HT molecules. The droplet size and the evaporation of residual solvent in the droplet determine the film morphology. Ultraviolet–visible absorption spectroscopy was used to identify the ordering of P3HT molecules in the films. The self-assembly of P3HT molecules took place during the solvent evaporation which can be controlled by a combination of the pulse amplitude and the pulse interval. With an appropriate combination of the amplitude and the interval, the ESD produced a P3HT thin film with high chain ordering.
(© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)