Inkjet printed perylene diimide based OTFTs: Effect of the solvent mixture and the printing parameters on film morphology

In the present work, we report the influence of the solvents on the morphology and the uniformity of inkjet printed n-type (electron-transporting) perylene diimide (PDI-8CN2) semiconductor films on SiO2 substrates. In particular, a solvent mixture composed by o-dichlorobenzene and chloroform was employed and the semiconductor crystalline structure was investigated as a function of the mixing ratio of the component solvents. For each mixture composition, the printing parameters such as substrate temperature and drop overlapping degree, were optimized to improve the reproducibility of the deposition process and the structural quality of the final films. Organic thin film transistors were fabricated and electrically characterized. The electrical measurements suggest that for the devices with larger active areas, the solvent mixture approach improves the performances of OTFTs in comparison with the use of pure o-dichlorobenzene solution.