Ho Jun Song

Development of Organic Semiconductors Based on Quinacridone Derivatives for Organic Field-Effect Transistors: High-Voltage Logic Circuit Applications

Poly[quinacridone-alt-quaterthiophene] (PQCQT) was synthesized, using a Suzuki coupling reaction, to investigate the potential of quinacridone derivatives as organic semiconductors in organic fieldeffect transistors (OFETs) and circuits. A PQCQT film annealed at 150 °C yielded quite high field-effect performances, including a hole mobility of

Effects of Organic Acids and a Fluoropolymer on the Conductivity and Transparency of Poly(3,4-ethylenedioxythiophene) Films

2.0 \times 10^{-2}

Solution-processed interlayer of n-type small molecules for organic photovoltaic devices: Enhancement of the fill factor due to ordered orientation

cm2/(Vs). In addition, to confirm the feasibility of using PQCQT in high-voltage circuit applications, electrical behaviors of PQCQT-based OFETs were described by extracting the model parameters of the industry standard compact Berkeley short-channel IGFET model. From the developed OFET model parameter set, we successfully evaluated the circuit operation of a p-type organic inverter with a frequency of 45.5 kHz in an 80 V supply condition.

Conjugated polymer consisting of benzothiadiazole and phenazine as donor materials for organic photovoltaics

Using two organic acids with similar structures, we could fabricate poly (3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)-based conductive thin films with improved transparency and surface resistance. Sulfosuccinic acid showed better performance than p-toluenesulfonic acid with respect to the surface resistance and transparency, because sulfosuccinic acid has more acid group than that of p-toluenesulfonic acid, which shows efficient phase separation of PEDOT. This leads to the growth of PEDOT grains and decrease of the PSS shell. It was presumed that the PEDOT grain isolated from the pristine film swelled and grew, thereby improving the connectivity and facilitating the charge transfer. In addition, addition of a fluoropolymer enhanced the hydrophobicity of the surface of the film, thereby enhancing the durability of the film by increasing the water resistance and water permeability. When sulfosuccinic acid was added, the PEDOT:PSS film showed low surface resistance (106 Ω/sq) and high transparency (>89%). In addition, addition of the fluoropolymer resulted in a lower surface resistance (95 Ω/sq) and higher transparency (>89 %). The durability of the film was maintained for 3 days in the conventional case, but the durability was maintained up to 20 days on addition of the fluoropolymer.