Christian May

Organic solar cells on indium tin oxide and aluminum doped zinc oxide anodes

The authors compare organic solar cells using two different transparent conductive oxides as anode: indium tin oxide (ITO) and three kinds of aluminum doped zinc oxide (ZAO). These anodes with different work functions are used for small molecule photovoltaic devices based on an oligothiophene derivative as donor and fullerene C60 as acceptor molecule. It turns out that cells on ITO and ZAO have virtually identical properties. In particular, the authors demonstrate that the work function of the anode does not influence the Voc of the photovoltaic device due to the use of doped transport layers.

Highly efficient p-i-n-type organic light emitting diodes on ZnO:Al substrates

Aluminum doped zinc oxide (ZAO) is presented in this letter as an alternative transparent electrode: optimized ZAO films offer excellent parameters for organic light emitting diodes (OLEDs). The ZAO films are applied to various p-i-n-type OLEDs. By using green phosphorescent molecules in a double emitter structure, very high efficiencies were obtained, namely, 54.6cd∕A and 61.5lm∕W for 100cd∕m2 at 2.78V. Additionally, white OLEDs on ZAO demonstrated pure white emission independent of the luminance and high efficiencies of 12.6cd∕A and 14.5lm∕W for 100cd∕m2 at 2.6V, which is comparable to indium-tin-oxide based white OLEDs.

19.4: Large Area p-i-n Type OLEDs for Lighting

An OLED for lighting applications was successfully demonstrated on a 150mm ×150mm substrate with ITO anode. Additionally, ZnO: Al (ZAO) as an alternative transparent electrode for OLEDs was fabricated and applied to highly efficient p-i-n type green OLEDs and a white OLED for lighting applications. These devices showed similar performance as ITO anode based OLEDs.

Second generation OLED devices and systems: inline evaporation, highly efficient OLED devices, and novel driver/controller ASICs

Organic light-emitting diodes (OLED) have to be improved to achieve new market segments in displays and lighting applications. We present important steps towards achieving this goal in a combination of highly efficient devices, manufacturing and new driving aspects. It is generally expected that the manufacturing methods have to be made more efficient to achieve large market penetration. We firstly present results on a highly efficient RGB-OLED-system with doped transport layer, manufactured in the worldwide first vertical In-Line set-up. Additionally a second-generation passive matrix OLED controller/driver IC was developed. Though the design was application-specifically directed for the onto integration into an OLED minidisplay panel module (e.g., by pad layout design being closely related to display connection schemes), versatile service in various applications was focused on. Therefore, in general they may also act as application-specific standard products (ASSP), if their built-in functions provide compatibility to a wide range of passive-matrix OLED panels. Additionally, the second generation supports various PMOLED display resolutions, area or full-color (RGB) operating modes and circuit techniques for OLED devices lifetime improvement.

Power electronics in railway lighting systems

Up to 20 percent of the generated electrical energy (according to the Department of Energy in the USA even 22 percent) is spent on lighting systems. Although the part consumed by lighting systems in railways is relatively small, there is the challenge to use the available technological options. Based on the predominantly used technology, the cold cathode fluorescent lamp with electronic ballast, the problems of using LEDs and OLEDs will be discussed.

High efficient pin orange organic light emitting diode fabrication with novel Al cathode using DC magnetron sputtering

In this study a high efficient p-i-n type orange organic light emitting diode (OLED) is presented. It is based on doped charge transport layers to realize low operating voltage and emitting layer which consists of alpha-NPD(4,4-bis [N-(1- naphtyl)-N-phenylamino]biphenyl) and Iridium(III)bis(2-methyldibenzo-[f,h]quinoxaline)(acetylacetonate) as a host and a phosphorescence dye dopant respectively. Organic layers are vacuum-sublimed on ITO-coated glass substrates in vertical inline deposition tool, and aluminium is deposited directly on organic layer by DC magnetron sputtering to form a cathode. Since sputter deposition of top electrode is known to damage organic layers and degrade OLED performance, various sputter process parameters are selected and applied for cathode formations, and the OLEDs are characterized by means of I-V-L measurements. The OLED characteristics are evaluated with the plasma factors based on sputter process parameters in order to explain the damage sources from sputtering process. The characteristics of OLEDs that cathodes are deposited by sputtering and evaporation are compared. The fabricated OLED which has the lowest damage level exhibits almost comparable result to the OLED that the cathode is deposited by evaporation. The OLED shows good performances of driving voltage of 4.25 V and luminous efficacy of 7.77 lm/W and current efficiency of 10.68 cd/A at 1000cd/m2.

46.4: Up-Scaling of OLED Manufacturing for Lighting Applications

First results of a newly developed Gen-2 manufacturing system for lighting and signage applications based on organic light-emitting diodes (OLED) are presented. High efficiency of 47.8 cd/A at C.I.E color coordinates of 0.39/0.38 at 1000 cd/m2 was reached in forward emission applying a two-unit stacked white architecture. 100×100 mm2-lighting-tiles showed a luminous efficacy of 18.5 lm/W (C.I.E color coordinates 0.45/0.43) based on integrating sphere measurements. Process reproducibility was analyzed in terms of run-to-run, day-to-day and tile-to-tile parameter variation.

72.4: Invited Paper: Novel Approaches for OLED Lighting

In this paper, we discuss novel approaches for organic light-emitting diode (OLED) lighting application. In particular, we discuss OLED deposited by vacuum deposition on flexible substrates such as plastic and metal foils. We discuss the specific challenges of OLED design for such substrates, in particular when top-emitting structures are required. Furthermore, we discuss a novel vacuum roll-to-roll tool which is capable of depositing oligomer OLED with high efficiency.