Controlled pattern formation of poly [2-methoxy-5(2′-ethylhexyloxyl)-1,4-phenylenevinylene] (MEH-PPV) by ink-jet printing

A detailed survey on the processing of poly[2-methoxy-5-(2'-ethylhexyloxyl)-1,4-phenylenevinylene] (MEH-PPV) solutions via ink-jet printing and the subsequent characterization of the resulting films is reported. The printability of MEH-PPV dissolved in different solvents, and with varied concentrations, is studied. Limitations of the printability of highly concentrated polymer solutions are overcome by using ultrasonication. The pattern formation of the resulting lines is explained in relation to the contact angle formed by the MEH-PPV solution on the substrate and interchain interactions. A uniform thickness distribution of MEH-PPV films is obtained when toluene is used as the solvent. Further improvement on the surface quality of the lines is achieved by optimizing the printing parameters. The line stability as a function of the print-head velocity is also studied. Additionally, current-voltage (I-V) characteristics and the morphology of the MEH-PPV films, as determined by atomic force microscopy, are discussed.