Moisture-induced hysteresis of pentacene thin film transistors with cross-linked poly(4-vinylphenol) gate dielectrics.

The time variable electrical characteristics of pentacene thin-film transistors (TFTs) with poly(4-vinylphenol) gate dielectrics were investigated under various relative humidity conditions and the effect of moisture on the hysteresis behavior of the pentacene TFTs was studied. One possible cause of the hysteresis behavior is the presence of inherent hydroxyl groups in bulk or surface of the polymeric dielectric, which make the gate dielectric polar, but the hysteresis behavior of the pentacene TFTs was found to depend strongly on the relative humidity and to increase with an increase of the moisture in the surrounding atmosphere. With a time-scalable investigation, it was also found that the adsorption of moisture onto the pentacene layer is the main reason for the hysteresis even with the -OH rich polymeric dielectric. The hysteresis behavior was found to be significantly reduced by suppression of moisture or other moisture-induced impurities, such as the encapsulation of the devices with glass.

Prevalence of primary open-angle glaucoma in central South Korea the Namil study.

PURPOSE: To assess the prevalence of primary open-angle glaucoma (POAG) in the Namil-myon area in central South Korea. DESIGN: A cross-sectional, epidemiologic study in a defined population. PARTICIPANTS: Residents aged ≥ 40 years in Namil-myon, a rural agricultural area in central South Korea. METHODS: Each subject underwent a screening that consisted of an interview and ophthalmic examinations, including visual acuity measurement, autorefraction, anterior segment evaluation by optical biometry, slit-lamp examination, Goldmann applanation tonometry, binocular optic disc evaluation, fundus photography, pachymetry, gonioscopy, and screening visual field test using frequency doubling technology. Subjects with suspected glaucoma were referred for definitive examinations. Standard automated field tests and retinal nerve fiber layer analysis using optical coherence tomography (Stratus OCT) or scanning laser polarimetry (GDx VCC) were performed. A diagnosis of glaucoma was made based on the optic disc shape, retinal nerve fiber layer appearance, perimetric results, and other ocular findings. MAIN OUTCOME MEASURES: Prevalence of POAG, mean intraocular pressure (IOP), and mean central corneal thickness (CCT). RESULTS: Of 1928 eligible residents in the area, 1532 (79.5%) participated in this study. The estimated prevalence of POAG in the population aged ≥ 40 years was 3.5% (95% confidence interval [CI], 2.7%-4.3%). The prevalence of POAG with an IOP of ≤ 21 mmHg was 2.7% (95% CI, 2.1%-3.3%), and the prevalence of POAG with an IOP of ≥ 22 mmHg was 0.8% (95% CI, 0.4%-1.2%). The mean IOP for POAG eyes (16.3 ± 4.6 mmHg) was significantly higher than nonglaucomatous eyes (13.3 ± 2.7 mmHg; P = .001). The mean CCT of POAG eyes with an IOP of ≤ 21 mmHg was 528 ± 26 µm, and that of POAG eyes with an IOP ≥ 22 mmHg was 531 ± 37 µm; these values were not significantly different from that of nonglaucomatous eyes (530 ± 31 µm; P = .943 and .996, respectively). CONCLUSIONS: The prevalences of POAG and POAG with an IOP ≤ 21 mmHg in the Namil-myon region of central South Korea were higher than that in most previous reports worldwide, but were similar to the reported rates in black and Japanese populations. The mean IOP of POAG eyes was higher than nonglaucomatous eyes, but the mean CCTs were not different. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Maskless laser direct patterning of PEDOT/PSS layer for soluble process organic thin film transistor.

In this work, we have fabricated TIPS-pentacene TFTs with conductive polymer (3,4-ethylenedioxythiophene):poly(4-stylenesulfonate) (PEDOT:PSS) source/drain electrodes which is patterned by maskless laser direct patterning (LDP). The 5-microm resolution of source and drain patterns with PEDOT:PSS were clearly defined. Furthermore, the OTFTs with 10-microm channel length were successfully achieved by exposing the focused Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser beam onto the spin-coated PEDOT:PSS films and developing with deionized water. The electrical performance of the TIPS-pentacene TFTs with PEDOT:PSS source/drain electrodes were improved with decrease of the sheet resistance of PEDOT:PSS films when the PEDOT:PSS films were annealed at the temperature above 200 degrees C.