Bias-Dependent Generation and Quenching of Defects in Pentacene

We describe a defect in pentacene single crystals that is created by bias stress and persists at room temperature for an hour in the dark but only seconds with 420nm illumination. The defect gives rise to a hole trap at Ev + 0.38eV and causes metastable transport effects at room temperature. Creation and decay rates of the hole trap have a 0.67eV activation energy with a small (108 s-1) prefactor, suggesting that atomic motion plays a key role in the generation and quenching process.Comment: 10 pages, 3 figure

Bistable organic materials in optoelectrical switches: Two-electrode devices vs. organic field effect transistors

The paper presents a short overview of research into properties of organic materials and structures that could be used in optoelectrical switches, i.e., switches in which changes in electrical properties are triggered by light of appropriate wavelengths. In particular, described are the structures acting by virtue of reversible photochemical reactions occurring in photochromic molecular materials

Electrolytic simulation of airfloil flow

Airfoil flow simulation tests were carried out in a 20-inch diameter double layer circular electrolytic tank. Results of the tests indicate that the tank very closely approximates ideal conditions. The double layer circular electrolytic tank is shown to generate a very large rectangular tank. Formulas were derived to show that this double layer tank is valid for the analogy between fluid velocity and voltage gradient. Tests were performed on a five inch diameter cylindrical model. The first series of tests was performed with the ground plane very far from the model surface. Electrical current to the model was adjusted so that circulation and lift could be calculated for different angles of stagnation point on the model. The second series of tests was performed with suitable electrodes so the model would be near the ground plane. The purpose of these tests was to investigate how circulation, lift, and effective velocity varied when model to ground plane distance was varied. The appendix contains data in a format similar to that in which it was used in the ALWAC IIIE computer to obtain numerical results. AIso in the appendix are results of investigations on circular airfoils made by other investigators using conducting sheets and a wind tunnel. A discussion of equipment used and improvements that could be made is included