Copyright (c) 2009 All rights reserved. http://works.bepress.com/dbraun Recent documents in David Braun en-us Sun, 31 May 2009 05:15:45 PDT 3600 http://works.bepress.com/dbraun/27 http://works.bepress.com/dbraun/27 Wed, 01 Apr 2009 16:51:29 PDT Control device for an electroluminescent display device, comprising an active layer of a semiconducting polymer of, for example pixels arranged in the form of a matrix, reducing flicker and crosstalk. The control device may be based on voltage control at which voltages across the pixels are at least 1.6 V, but is preferably based on current control, at which the duration of the data pulses determines the grey level. Aemilianus G. J. Staring Patents http://works.bepress.com/dbraun/26 http://works.bepress.com/dbraun/26 Wed, 01 Apr 2009 16:51:28 PDT A description is given of an electroluminescent device (1) having an LED structure, which is composed of an active layer (7) of oriented liquid-crystalline and electroluminescent compounds and a transparent positive electrode layer (5) which is preferably made from an electroconductive polymer. By previously rubbing the electrode layer (5) in one direction with a velvet cloth, an orientation is induced in the molecules in the active layer (7), the orientation being frozen by cooling or polymerization. The electroluminescent device (1) emits polarized light whose direction of polarization is parallel to the direction of rubbing. Rifat A.M. Hikmet Patents http://works.bepress.com/dbraun/24 http://works.bepress.com/dbraun/24 Wed, 01 Apr 2009 16:51:27 PDT A description is given of an electroluminescent (EL) device (1) composed of polymeric LEDs comprising an active layer (7) of a conjugated polymer and a transparent polymeric electrode layer (5) having electroconductive areas (51) as electrodes. Like the active layer (7), the electrode layer (5) can be manufactured in a simple manner by spin coating. The electrode layer (5) is structured into conductive electrodes (51) by exposure to UV light. The electrodes (9) and (51) jointly form a matrix of LEDs for a display. When a flexible substrate (3) is used, a very bendable EL device is obtained. Aemilianus G. J. Staring Patents http://works.bepress.com/dbraun/25 http://works.bepress.com/dbraun/25 Wed, 01 Apr 2009 16:51:27 PDT Visible light LEDs are produced having a layer of conjugated polymer which is cast directly from solution or formed as a gel-processed admixture with a carrier polymer. The LEDs can be formed so as to emit polarized light. Alan J. Heeger Patents http://works.bepress.com/dbraun/29 http://works.bepress.com/dbraun/29 Wed, 01 Apr 2009 16:51:15 PDT An illumination system has an active layer which includes an electroluminescent material, the active layer being located between an optically transparent electrode layer and a reflective electrode layer. A reflective polarizer is present at a side of the transparent electrode layer facing away from the active layer. A sub-beam incident on the polarizer and having an unwanted polarization is reflected back to the active layer, where it is again partially depolarized to recover a component having the desired state of polarization. The invention also relates to a flat-panel picture display device which includes such an illumination system. Dirk J. Broer Patents http://works.bepress.com/dbraun/28 http://works.bepress.com/dbraun/28 Wed, 01 Apr 2009 16:50:59 PDT Visible light LEDs are produced having a layer of conjugated polymer which is cast directly from solution or formed as a gel-processed admixture with a carrier polymer. The LEDs can be formed so as to emit polarized light. Alan J. Heeger Patents http://works.bepress.com/dbraun/23 http://works.bepress.com/dbraun/23 Fri, 20 Mar 2009 10:05:00 PDT Passive matrix displays based on polymer and organic light-emitting diodes (LEDs) suffer from crosstalk, the emission of light from pixels other than those selected. This article explores the topic of crosstalk both with an approximate but analytic model and by means of more exact circuit simulation in order to explain the causes of crosstalk and to quantify the consequences. We conclude that crosstalk has implications for display power consumption. David Braun Articles http://works.bepress.com/dbraun/22 http://works.bepress.com/dbraun/22 Fri, 20 Mar 2009 10:04:59 PDT The transient electroluminescence from polymer light-emitting diodes is reported. When the devices are mounted on a microstrip transmission line, the temporal response is limited by the electrode geometry, with rise and fall times below 50 ns. With low duty-cycle pulses (0.5%) the electroluminescence intensity remains proportional to the current at values up to 10 A/cm2, two orders of magnitude greater than possible under direct current operation. Since the spectral blue-shift observed at high current levels (with power dissipation above 1 W/cm2) indicates significant sample heating, still higher levels should be possible with proper thermal management. David Braun Articles http://works.bepress.com/dbraun/20 http://works.bepress.com/dbraun/20 Fri, 20 Mar 2009 10:04:58 PDT We report the observation of the Schottky effect at the interface between a metal and a semiconducting polymer by means of internal photoemission spectroscopy. The bias dependence of the barrier provides information on the electrical properties of the polymer. G. Rikken Articles http://works.bepress.com/dbraun/21 http://works.bepress.com/dbraun/21 Fri, 20 Mar 2009 10:04:58 PDT We report visible light emission from Shottky diodes made from semiconducting polymers, confirming the discovery by the Cambridge group [Nature 347, 539 (1990)]. Our results demonstrate that light-emitting diodes can be fabricated by casting the polymer film from solution with no subsequent processing or heat treatment required. Electrical characterization reveals diode behavior with rectification ratios greater than 104. We propose that tunneling of electrons from the recitifying metal contact into the gap states of the positive polaron majority carriers dominates current flow and provides the mechanism for light emission. David Braun Articles