Teun M. Klapwijk

Efficient Intermolecular Charge Transport in Self‐Assembled Fibers of Mono‐ and Bithiophene Bisurea Compounds

Hydrogen bonds between urea units allow self-organization of π systems in mono- and bithiophenes into fibers as shown schematically. In these fibers there is a surprisingly high mobility of charge carriers as determined by pulse-radiolysis time-resolved microwave conductivity measurements.

Effect of the top electrode work function on the rectification ratio of light-emitting diodes (LEDs) based on poly(3-octylthiophene)

Electroluminescence efficiency and current-voltage characteristics of conjugated polymer poly(3-octylthiophene) (P3OT) light emitting diodes (LEDs) are discussed in terms of the presently popular band model. Devices were studied in forward and reverse mode of operation, with different types of top contacts to show the dominance of the top electrode workfunction on device properties. Changing the workfunction of the top contact with only 0.9 eV (from Au to Al) results in a change in the preferred current direction, corresponding to a change in the rectification ratio of the diodes of effectively 6 orders of magnitude. When Au is used as a top electrode, no electroluminescence was observed, because the barrier for electron injection is too high. The observation of light emission in the reverse mode of operation for ITO/P3OT/Al is a result of direct carrier tunneling into the transport bands at high electric fields.

345-GHz facility SIS receiver for the JCMT

Receiver B3 is a common-user facility instrument for the JCMT and was commissioned in December 1996. It includes the following features: (1) Frequency coverage of 315 to 372 GHz with optimum performance at 345 GHz. (2) Two spatially- coincident channels with orthogonal linear polarizations. (3) An IF of 4 GHz with an instantaneous bandwidth of 1.7 GHz in each channel. (4) Single side-band capability with the rejected side-band terminated on a cold load. (5) High- efficiency, frequency-independent optics. (6) Independent adjustment of the local oscillator power to the two mixers. (7) Internal ambient and cold loads for accurate receiver calibration. (8) Fully automated operation.