Highly sensitive permeation measurements are crucial for the characterization and development of polymeric substrates for flexible display applications. In particular, organic light-emitting devices require substrates with extremely low permeation rates for water and oxygen. Here we demonstrate a concept for measuring ultralow permeation rates. The amount of oxidative degradation in a thin Ca sensor is monitored by in situ resistance measurements. The benefits of this technique are demonstrated for polyester foils with single- and double-sided barrier coatings. A sensitivity limit is imposed by the quality of the encapsulation. The resulting base line contribution to the water vapor transmission rate of a glass reference is below 10−6 g/m2 day at accelerated test conditions.

Due to their outstanding properties, e.g., good contrast, wide viewing angle, low power consumption, and self-emission organic light-emitting (OLE) displays on the basis of conjugated polymers are on the verge of commercialization. Two major disadvantages of the current processing technique for the polymers—spin coating—are the material waste and the difficulties involved in patterning multichrome or even full-color displays. Therefore, we investigated the screen-printing technique for the production of OLE displays. In this letter, we present performance data and images of screen-printed OLE diodes. They are already comparable to spin-coated ones. We observed luminance of 10 000 cd/m2 at 8 V and peak efficiencies exceeding 10 cd/A for green diodes. These data indicate that printed organic displays have the potential to replace “classical” spin-coated devices.

Organic light-emitting diodes were fabricated on a 125-μm-thick polyethylene terephthalate substrate covered with 100 nm indium tin oxide. The luminance–current–voltage performance and the emission spectrum of the devices are investigated in the bent state under mechanical stress at different bending radii. Down to a curvature of 15 mm, no significant decrease in the device performance is found compared to the relaxed state, as well as to conventional devices on glass substrates.

Abstract. We focus on the determination of the internal luminescence quantum efficiency of a green-emitting organic light-emitting diode (OLED). By considering different geometrical configurations of OLED thin-film stacks, we elucidate the role of the internal luminescence quantum efficiency of the emitter in the thin-film microcavity. Combining optical simulations with experimental results, a comprehensive efficiency analysis is performed. Here the electroluminescence of a set of OLEDs is characterized. Additionally, the devices are characterized using time-resolved photoluminescence measurements. The experimental data are analyzed using optical simulations. This analysis leads to a quantification of internal luminescence quantum efficiency and allows conclusions about competing mechanisms resulting in nonradiative recombination of charge carriers. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

No abstract

No abstract

Semprius has a novel micro-cell based approach that addresses the cost, performance and reliability requirements of high concentration photovoltaic systems. A design that has a geometric concentration ratio of >1100 suns and three-junction 0.36 mm 2 micro-transfer printed cells is now complete. A module efficiency of 33.9% at a direct normal irradiance of 850 W/m 2 and cell temperature of 25 C has been independently validated for this design by the Instituto de Energia Solar at the Universidad Politecnica de Madrid. This is the highest measured module efficiency for any PV module, designed for commercial use. Several research, development and demonstration (RD&D) systems have been installed with these modules to collect early on-sun data and validate the technology. This paper presents module characterization and on-sun system results from a 3.5-kWp RD&D system installed at Instituto de Sistemas Fotovoltaicos de Concentracion, Puertollano, Spain by Semprius and Siemens. In addition, results from cleaning experiments and thermal performance of the system are presented from another RD&D system in Tucson. Comparisons of the performance of the Tucson RD&D system with co-located one-axis Si and fixed-tilt Si systems are also presented.

Optical Technologies have conquered the world" -their economic key data showed an impressive growth in the past couple of years, and the predictions for the up-coming years keep the expectations high 1, 2 . In the case of OLED (Organic Light Emitting Diode) lighting, e.g. IDTechEx is predicting a worldwide market growth from 50 million USD in 2009 to 3.3 billion USD in 2012 3 .LED and OLED technology, although both being referred to as solid state lighting, are rather complementary in their characteristics. Whereas LEDs are high efficient point light sources, OLEDs cover large area, diffuse lighting applications which can follow the increased awareness for creation of personalized atmosphere. Ambience and mood lighting can be perfectly realized by the means of OLED large area illumination which will pave the way for applications that up to now could not have been realized.OLED lighting technology rests on three pillars at the same time, the basic performance like efficiency and lifetime, the unique features, and costs. These key challenges and their impact on various applications will be discussed.