We report recent advances in the development of low power consumption, emissive, flexible active matrix displays through integration of top emitting phosphorescent OLED (T-PHOLED) and poly-Si TFT backplane technologies. The displays are fabricated on flexible stainless steel foil. The T-PHOLEDs are based on UDC phosphorescent OLED technology, and the backplane is based on PARC's Excimer Laser Annealed (ELA) poly-Si TFT process. We also present progress in operational lifetime of encapsulated T-PHOLED pixels on planarized metal foil and discuss PHOLED encapsulation strategy.
In this paper we describe the applications and status of OLED technology to produce displays ideally suited for mobile applications. In particular, we focus on phosphorescent OLED (PHOLED) technology to reduce display power consumption and flexible OLED (FOLED) technology to reduce the display thickness and weight. We show that PHOLED displays can consume less power than an equivalent backlit AMLCD, and have excellent visual performance characteristics which make these displays highly desirable for portable communication devices. We will then describe an example of a unique communication device, a Universal Communication Device (UCD), based on flexible PHOLED technology, to produce a powerful communication device with a low power consumption and a light weight and very portable form factor. This device, enabled by a roll-out phosphorescent active-matrix display fabricated on a metallic or plastic substrate, is of great interest for a range of both consumer and military products.
In this paper we will outline the technical challenges and progress towards enabling a novel communication device based on a roll-out, low power consumption, OLED display. Advanced mobile communication devices require a bright, high information content display in a small, light-weight, low power consumption package. We believe that phosphorescent OLED (PHOLED) technology fabricated on a truly flexible substrate, enables a mobile Universal Communication Device (UCD) to offer a high information content display in an extendable form, while rolling up into a small form factor when not in use. This communication device is of great interest for a range of both consumer and military applications. From the display perspective, the key component is achieving a long-lived, low power consumption display. We believe the OLEDs are the preferred display media, and in this talk we will outline our flexible phosphorescent OLED technology. The key to reliable operation is to ensure that the organic materials are fully encapsulated in a package designed for repetitive flexing. UDC has been developing long-lived flexible OLED (FOLED) displays based on plastic substrates and multi-layer monolithic encapsulation. Recent progress in this area will also be reported. Finally, we will outline the backplane requirements for flexible OLED displays and compare the various technology options that can be used to fabricate the UCD.
High-efficiency electrophosphorescent organic light emitting devices (OLEDs), based on triplet emission, is an enabling technology for low power full-color OLED displays. In addition, top emission OLED architectures can be used to maximize display aperture ratio and pixel current densities. In this paper we report on recent results in red, green and blue phosphorescent and top emission OLEDs and discuss the benefits that these attributes have on both active and passive matrix display performance.
We describe the performance of mixed-layer, small molecule organic light-emitting devices (OLEDs) that are step-graded from a mostly hole transporting layer (HTL) to a mostly electron transporting layer (ETL) from anode-side to cathode-side, respectively. The devices are based on a green, electrofluorescent dopant and achieve luminous efficiencies of > 4.5 lm/W and 10 cd/A. These efficiencies are significantly higher than those of a uniformly mixed device, i.e., a device in which the HTL and ETL are uniformly mixed, but lower than those of a conventional heterostructure device employing the same dopant material. Operating lifetime of the graded mixed OLEDs, however, is much improved over the heterostructure device. We then compare the performance of fluorescent OLEDs at high current drive to that of phosphorescent OLEDs at high current drive in the context of passive matrix driven display suitability.
Michael Weaver, Anna Chwang, Mark Rothman, Jeff Silvernail, Michael Hack, Julie Brown, Paul Burrows, Gordon Graff, Mark Gross, Peter Martin, Michael Hall, Eric Mast, Charles Bonham, Wendy Bennett, M. Zumhoff
Organic light emitting diodes (OLEDs) have recently entered the market place as a competitive flat panel display technology. OLED displays are moving rapidly from small passive matrices (i.e. <3 inches diagonal) to full color active matrices based on rigid substrates. This paper is focused on new developments to help enable flexible OLED (FOLED) displays. Presented here will be high efficiency phosphorescent OLED displays that can be used in either passive or active matrix drive configurations. Passive matrix displays incorporating this technology fabricated on flexible substrates are also reported. These early demonstrations of flexible OLED displays illustrate the promise for a whole new generation of display products based on the design dimension of flexibility.
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