Organic field-effect transistors (OFETs) were fabricated with a high-dielectric-constant and high-permittivity titanium dioxide (TiO 2 ) as a gate insulator and regioregular poly(3-hexylthiophene-2,5-diyl) (RR-P3HT) as the electronically active semiconductor. Positive OFET characteristics were obtained with a low threshold voltage (+3 V) and high field-effect mobility (3:73 Â 10 À3 cm 2 V À1 s À1 ). The dielectric material (TiO 2 ) was prepared by the sol-gel technique and the gate insulator layer was fabricated by spin coating. The RR-P3HT thin films were fabricated by drop casting with different solution concentrations. The thickness of the thin films was measured using the surface profile measuring system. The fabricated thin film structure was analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), and UV-visible absorption spectra. The X-ray result shows that the drop-cast RR-P3HT thin film has a high crystallinity on the TiO 2 surface, which leads to the high field-effect mobility of the OFET. The results show that the OFET performances are not only dependent on the orientation and crystallinity of the polymer semiconductor, but that also the gate dielectric properties, surface roughness, and interface properties between the gate and semiconductor layers are very important for the efficient performance of the OFET.

Poly (3-hexylthiophene)/polymethylmethacrylate [P3HT/PMMA] composite thin film was prepared by the spin-coating method by composing a prism-coupled waveguide. The UV-visible spectrum was recorded in the range of 300-900nm to determine its optical absorption property. An Nd:YAG laser with a wavelength of 1064nm, a pulse width of 5ns, and a repetition frequency of 10Hz was used for optical bistability measurements. The optical bistable characteristics of the prism-coupled waveguide comprised of P3HT/PMMA composite thin film was measured for different input laser power intensity using optical bistable measuring equipment. The effect of organic gas treatment on the optical bistable behavior of the P3HT/PMMA quasi-waveguide was observed. The effect of PMMA molecular weight on the optical bistability of the P3HT/PMMA waveguide was also investigated.

No abstract

No abstract

Organic solar cell devices were fabricated using poly[9-(1-octylnonyl)-9H-carbazole-2.7-diyl]-2.5-thiophenediyl-2.1.3-benzothiadiazole-4.7-diyl-2.5-thiophenediyl] PCDTBT/ [6,6]-phenyl C 71 butyric acid methyl ester (PC71BM) active layer deposited by spin coating. Moreover, the relationship between solar cell performance and buffer layer thickness was investigated by spin coating speed and AFM imaging of the buffer layer surface. The performance of the organic solar cell with spin-coated active layer was then evaluated, and the power conversion efficiency of the solar cell was determined to be > 5%.