Organic small molecule field-effect transistors with Cytop(TM) gate dielectric: eliminating gate bias stress effects

We report on organic field-effect transistors with unprecedented resistance against gate bias stress. The single crystal and thin-film transistors employ the organic gate dielectric Cytop(TM). This fluoropolymer is highly water repellent and shows a remarkable electrical breakdown strength. The single crystal transistors are consistently of very high electrical quality: near zero onset, very steep subthreshold swing (average: 1.3 nF V/(dec cm2)) and negligible current hysteresis. Furthermore, extended gate bias stress only leads to marginal changes in the transfer characteristics. It appears that there is no conceptual limitation for the stability of organic semiconductors in contrast to hydrogenated amorphous silicon.Comment: 4 pages, 3 figures, to be published in Appl. Phys. Let

Quinoid heteropentacenes as promising organic semiconductors for field-effect transistor applications

We report on a quinoid heteropentacene as p-type semiconductor in organic field-effect transistors. Both single crystal and thin-film transistors were fabricated with 7,14-diphenyl-chromeno[2,3-b]xanthene (DPCX). In this small molecule organic semiconductor the field-effect mobility is as high as 0.16 cm2/V s in single-crystal devices and 0.01 cm2/V s in thin-film devices. In addition, the devices show favorable properties such as near zero onset/threshold voltages and a small current hysteresis. X-ray diffraction experiments show the molecules to be arranged in slipped stacks and to have a flat backbone in the crystals. For thin films of DPCX the situation is complicated by the coexistence of a thin-film phase with the bulk phase. However, a comparison of DPCX thin films on octadecyltrichlorosilane (OTS)-treated and bare SiO2 gate dielectrics provides clear evidence that the OTS surface treatment leads to organic thin films with a better structural order. The low-cost synthesis and purification of DPCX along with the improved processability and the good electrical characteristics suggest that quinoid heteropentacenes are promising materials for organic field-effect transistor

Clinical practice patterns in indirect peroral cholangiopancreatoscopy : outcome of a European survey

Background and aims Indirect peroral cholangiopancreatoscopy (IPOC) is a relatively new diagnostic and therapeutic tool for biliopancreatic diseases. This international survey aimed to evaluate clinical practice patterns in IPOC among endoscopists in Europe. Methods An online survey was developed comprising 66 questions on the use of IPOC. Questions were grouped into four domains. The survey was sent to 369 endoscopists who perform IPOC. Results 86 respondents (23.3%) from 21 different countries across Europe completed the survey. The main indications for cholangioscopy were determination of biliary strictures (85 [98.8%]) and removal of common bile duct or intrahepatic duct stones (79 [91.9 %]). accounting for an estimated use of 40% (interquartile range [IQR] 25-50) and 40% (IQR 30-60), respectively, of all cases undergoing cholangioscopy. Pancreatoscopy was mainly used for removal of pancreatic duct stones (68/76 [89.5%]), accounting for an estimated use of 76.5% (IQR 50-95) of all cases undergoing pancreatoscopy. Only 13/85 respondents (15.3%) had an institutional standardized protocol for targeted cholangioscopy-guided biopsy sampling. IPOC with lithotripsy was used as first-line treatment in selected patients with bile duct stones or pancreatic stones by 24/79 (30.4%) and 53/68 (77.9%) respondents, respectively. Conclusions This first European survey on the clinical practice of IPOC demonstrated wide variation in experience, indications, and techniques. These results emphasize the need for prospective studies and development of an international consensus guideline to standardize the practice and quality of IPOC.Peer reviewe