The Effect Of Interface Modification On Inkjet Printed Organic Semiconducting Layer

Inkjet printing technology had been concerned by the researcher from the very beginning, for not only the "direct-writing" advantage, but also saving material and being mass-produced. The interface modification is one of the important methods to improve the uniformity of the inkjet printed film and produce the desired structure of the organic semiconducting layer.In this thesis, the effect of interface modification on inkjet printed organic semiconducting layer had been studied. The main contents include:(1) Three kinds of materials were used to prepare self-assembled monolayer. It’s found that the interface properties of the substrates had a great influence on the morphology of the inkjet printed droplet and film. When a bare SiO2layer was applied, the best field-effect mobility of inkjet printed OTFTs was only2.37×10-3cm2V-1s-1, with an on/off current ratio of102. When the PETS treatment or the PTS treatment was applied on the SiO2dielectric layer, the field-effect performances were substantially improved and the best field-effect mobility was enhanced to8.07×10-3cm-2V-1s-1and7.95×10-3cm-2V-1s-1, respectively and with an on/off current ratio of103.(2) Different doses of UV irradiation were applied to prepare a series of PS films with different solubility. It’s found that the solubility of the PS film had a great influence on the morphology of the inkjet printed droplet and film. The atomic force microscope and X-ray diffraction revealed that the inkjet printed dots and films with the best orientation and largest size of crystalline structure were obtained when0.417J cm-2UV irradiation was applied on the PS film. Meanwhile, an appropriate solubility was also vital to obtain high-performance printed devices. For the inkjet printed OTFT devices based on the original PS film, the field-effect mobility was only (2.08±2.82)×10-2cm2V-1s-1. When0.417J cm-2UV irradiation was applied on the PS film, the field-effect performances were substantially improved and the field-effect mobility was enhanced to (1.80±1.24)×10-1cm-2v-1s-1. However, when the doses of UV irradiation was increased to0.695J cm-2and1.854J cm-2, the field-effect mobility was decreased to (1.27±0.84)×10-1cm-2V-1s-1and (7.57±4.20)×10-2cm2V-1s-1, respectively.