Novel Light Extraction Enhancements for White Phosphorescent OLEDs

72649 Developing more power efficient lighting sources is critical for national and global economic and environmental wellness. For example, if the energy used for lighting in residential, commercial and industrial sectors could be reduced by 50% in the U.S., over $25B per year could be saved . Organic light emitting device (OLED) technology is now being developed as a new potential low cost, high efficiency source of solid state lighting. However, considerable research and development is required to both improve the device efficiencies, lifetimes, and reduce costs. Our goal is to realize an innovative approach to low cost solid state white light sources by combining two novel outcoupling schemes: microlens arrays and aperiodic gratings. We will achieve world record efficient phosphorescent OLED devices with power efficiency > 60 lm/W. The purpose of the Phase I program was to demonstrate a white light phosphorescent OLED (PHOLED) light source employing microlens arrays, which has a power efficiency > 15 lm/W at 800 nits luminance. To that end, we exceeded the Phase I efficiency goals by 60% by fabricating, on schedule, white PHOLEDs with microlenses having 24 lm/W at a luminance of 1,000 cd/m2. We believe that this program clearly demonstrated the technical feasibility of our approach, and it is for this reason that in this Phase II proposal we intend to further pursue this effort to develop PHOLEDs with even higher outcoupling efficiencies, and produce prototype lighting panels, which will allow us to more fully evaluate the performance of these technologies to produce commercially viable solid-state light sources for general illumination. In Phase II, UDC and Princeton University will demonstrate high power efficiency white phosphorescent OLED lighting panerls. The team will build on their successful Phase I program and demonstrate white PHOLEDS that have improved ourcoupling efficiency through the atttachment of microlens arrays, in addition to incorporating novel aperiodic gratings consisting of stacks of dielectric materials deposited on the OLED glass substrate. Specifically, the key objectives of Phase II are: Demonstrate the feasibility of aperiodic dielectric stacks at increasing the performance of white phosphorescent OLEDs Fabricate microlens arrays that are permanently attached to the OLED substrate Design and fagricate a prototype 3¿ x 3¿ white lighting array pane with the following characteristics: CRI>75, and power efficiency > 1m/W at lighting luminance levels of 1,000 cd/m2. Commercial Applications and Other Benefits as described by awardee: The anticipated benefits of this work will be to demonstrate a new path for highly efficient white light sources by introducing a new dimension to the device design, i.e. high power, thereby significantly reducing the size of the substrate necessary for devices to produce optical power (>800 lumens) for room lighting. In addition, by combining other efficiency enhancing techniques (e.g. aperiodic gratings to further increase the outcoupling efficiency) with white SOLED light sources, we believe that efficiencies >50 lm/W could be demonstrated within the next 2 years. In parallel with these efforts, the Team will also be undertaking more fundamental research and development on high-efficiency PHOLED devices so as to improve both lifetime and efficiency. The combination of all these innovations should lead to >100 lm/W white OLED light sources. Such products will create real benefits for end users, manufacturers, and the general public. These include: energy savings, economic savings, environmental savings, domestic energy independence, new lighting solutions, and the growth of a new industry and markets.