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Phenyltrimethoxysilane was used to modify SiO 2 insulator and significantly enhanced the pentacene based organic thin-film transistors (OTFTs). The crystal structure, surface morphology, molecular structure and microstructure of pentacene polymorphic films with and without the modifications were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and contact angle meter. XRD studies reveal a decreased tilt angle ( θ T ) of pentacene molecules from c -axis toward a -axis, indicating that polymorphs transformation from the “triclinic bulk” phase to the “thin film” phase and orthorhombic phase occurs. AFM images show that the surface roughness of gate insulators has no influence on performance of the pentacene based OTFT. These results provide strong evidence that the performance improvement of OTFT after PhTMS modification of SiO 2 insulator surface is related to the microstructure transformation of the semiconductor. It suggests that the modified-layer may alter the molecular geometry and further induce structural phase transitions in the pentacene films for the performance improvement.

The influence of evaporation conditions of organic semiconductor material tris(8-hydroxyquinoline)aluminium (Alq3) on the performance of organic light emitting diodes (OLEDs) is reported. In the process of organic material thermal evaporation, the chamber was dark or had white light from a 100 W filament lamp. The devices prepared in the dark show higher emission intensity and efficiency compared with the ones prepared in white light under the same driving voltage. Atomic force microscopy measurements show that surface morphology and phase of Alq3 thin films are quite different for the previous cases. The different evaporation conditions are found to have direct effects on the electrical and luminance performance. The Alq3 thin films prepared in the dark as active emission layers of OLEDs show higher intensity and efficiency.

In this paper, the influence of the ultraviolet (UV)–ozone treatment of indium tin oxide (ITO) surface and the active layer post-annealing treatment on the performance of organic solar cells were investigated. Bulk heterojunction organic solar cells based on the blend of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM) were fabricated. It is found that the devices with the UV–ozone treatment for 5 min on ITO substrates show the better performance, compared with the devices without this treatment. The results demonstrate that the short-circuit current density ( J sc ) and fill factor (FF) could be improved by the post-annealing treatment. The devices with both treatments together show the best performance, with the increase of J sc from 2.68 mA/cm 2 to 4.13 mA/cm 2 and the enhancement of FF from 32.2% to 38.8%. Therefore, the power conversion efficiency is improved from 0.62% to 1.08%. The morphology of the active layers with and without the post-annealing treatment was characterized by atomic force microscopy.