Peter Levermore

Phosphorescent organic light-emitting diodes for high-efficacy long-lifetime solid-state lighting

We report data for a pair of singlestack all-phosphorescent 15 × 15 cm 2 organic light emitting-diode (OLED) light panels with high efficacy, long lifetime, and very low operating temperature: Panel 1 has 62 lm∕W efficacy, CRI ¼ 81 and lifetime to LT70 ¼ 18;000 h at 1000 cd∕m 2 , while Panel 2 has 58 lm∕W efficacy, CRI ¼ 82 and lifetime to LT70 ¼ 30;000 h at 1000 cd∕m 2 . Operating at a higher luminance of 3000 cd∕m 2 , Panel 2 has 49 lm∕W efficacy with lifetime to LT70 ¼ 4000 h. Excellent panel lifetime is enabled by a stable light blue phosphorescent materials system. Panel temperatures are within 10°C of ambient temperature at 3000 cd∕m 2 . Panel 2 was further used as a building block to demonstrate an all-phosphorescent OLED luminaire for under-cabinet lighting applications. Operating at approximately 3000 cd∕m 2 , theluminairedelivers570lmwith52 lm∕Wtotalsystemefficacy,CRI ¼ 86andCCT ¼ 2940 K.© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/1.JPE.2.021205)

52.4: Highly Efficient Phosphorescent OLED Lighting Panels for Solid State Lighting

We present a 15 cm × 15 cm PHOLEDTM lighting panel that operates with 50 lm/W efficacy, CRI = 87, CCT = 3055 K and lifetime to LT70 ≅ 10,000 hrs at 1,000 cd/m2. We also present a panel with 58 lm/W efficacy, CRI = 86 and CCT = 2790 K at 1,000 cd/m2, and a small-area lighting pixel with 109 lm/W efficacy, CRI = 80, CCT = 3295 K and lifetime to LT70 ≅ 15,000 hrs at 1,000 cd/m2. A highly stable light blue phosphorescent host-emitter system is used to reduce power consumption, extend operational lifetime and demonstrate exceptional emission color stability with aging.

72.2: Phosphorescent OLEDs: Enabling Solid State Lighting with Lower Temperature and Longer Lifetime

We present a pair of 15 cm × 15 cm all-phosphorescent OLED light panels with high efficacy and extended operational lifetime. Panel 1 operates at 1,000 cd/m2 with power efficacy = 62 lm/W. At a higher luminance of 3,000 cd/m2, power efficacy = 49 lm/W, CRI = 82, CCT = 2,950 K and CIE 1931 (x, y) = (0.446, 0.417). Similar high efficacy performance is recorded for Panel 2, which has lifetime to LT70 ∼ 4,000 hrs at 3,000 cd/m2. Excellent lifetime is enabled by a new light blue phosphorescent materials system and by the use of efficient phosphorescent emitters that ensure very low panel temperature without any additional thermal management.

High-performance phosphorescent white-stacked organic light-emitting devices for solid-state lighting

In this work we report exceptional efficacy, lifetime and color stability for all-phosphorescent white stacked organic light-emitting devices (SOLED®s). We report data for all-phosphorescent white SOLED pixels with two emissive units connected in series by a charge generation layer (CGL). At 3,000  cd/m 2 , efficacy = 54 to 56  lm/W and lifetime to 70% of initial luminance LT70 ≈ 20,000  h, with color rendering index (CRI) = 82 to 83 and chromaticity meeting Energy Star criteria. We further report data for a 15  cm×15  cm white SOLED panel that operates at 3,000  cd/m 2 with 48  lm/W efficacy, CRI = 86 and chromaticity meeting Energy Star criteria. The panel has extremely low operating temperature that is only 6.4°C above ambient, and exceptional lifetime of LT70 ≈ 13,000  h when operated at 3,000  cd/m 2 .

43.3: Power Efficient AMOLED Display with Novel Four Sub-Pixel Architecture and Driving Scheme

We present a novel all-phosphorescent AMOLED pixel architecture with a red, green, light blue and deep blue sub-pixel design. The highly efficient light blue reduces power consumption by 33% compared to an equivalent conventional RGB display using a fluorescent blue sub-pixel. Furthermore, by using a light and deep blue sub-pixel layout, the lifetime of the display will be significantly increased due to the reduced on-time required for the deep blue sub-pixel. Here we demonstrate this new design in a 2.5-inch AMOLED panel.

66.4: Invited Paper: Challenges and Opportunities in Scaling Up OLED Lighting Devices

In this paper we discuss the challenges involved in scaling from small size pixels to large area OLED lighting panels, with specific focus on panel luminance uniformity, resistive loss and lifetime. We also discuss panel design and report results for a 15 cm × 15 cm phosphorescent OLED (PHOLED) lighting panel.

42.1 Invited Paper: High Efficiency Phosphorescent AMOLEDs: The Path to Long Lifetime TVs

In this paper we present results of blue PHOLED technologies, and outline different AMOLED display architectures, comparing their performance and power consumption. Projected operating temperatures of AMOLED TVs are correlated to device lifetimes to show the lifetime enhancements enabled by the power savings of phosphorescent OLEDs. These results allow us to analyze compelling technology packages for OLED TVs.

Development of phosphorescent OLED lighting panels for highly efficient solid state lighting

We present a 7.5 cm x 7.5 cm white PHOLEDTM lighting panel that delivers 1,000 cd/m2 with 68 lm/W efficacy, CRI > 80 and lifetime to LT70 ≈ 15,000 hrs. A simple all-phosphorescent device architecture, including a highly stable light blue phosphorescent emitter-host system, is used to reduce panel power consumption, extend operational lifetime and demonstrate exceptional emission color stability with aging.

Large-area high-efficiency flexible PHOLED lighting panels

Organic Light Emitting Diodes (OLEDs) provide various attractive features for next generation illumination systems, including high efficiency, low power, thin and flexible form factor. In this work, we incorporated phosphorescent emitters and demonstrated highly efficient white phosphorescent OLED (PHOLED) devices on flexible plastic substrates. The 0.94 cm2 small-area device has total thickness of approximately 0.25 mm and achieved 63 lm/W at 1,000 cd/m2 with CRI = 85 and CCT = 2920 K. We further designed and fabricated a 15 cm x 15 cm large-area flexible white OLED lighting panels, finished with a hybrid single-layer ultra-low permeability single layer barrier (SLB) encapsulation film. The flexible panel has an active area of 116.4 cm2, and achieved a power efficacy of 47 lm/W at 1,000 cd/m2 with CRI = 83 and CCT = 3470 K. The efficacy of the panel at 3,000 cd/m2 is 43 lm/W. The large-area flexible PHOLED lighting panel is to bring out enormous possibilities to the future general lighting applications.

All-phosphorescent white stacked organic LEDs for solid-state lighting

The global lighting industry is in transition. Inefficient light sources, such as the incandescent bulb, are being replaced by energy-efficient alternatives. Solid-state lighting in the form of LEDs and organic LEDs (OLEDs) offers a promising solution. Here, we focus on OLED lighting, which is a rapidly accelerating technology that offers power-efficient, high-quality illumination with unprecedented form factors (e.g., minimal thickness, flexibility, and transparency), and low operating temperatures. However to meet the demands of mainstream lighting applications, improvement in OLED device lifetime is still required. It is customary to report lifetimes for solid-state lighting (SSL) based on the time taken for emission to decay to 70% of initial luminance (LT70). The longest lifetime reported to date for a single-unit warm white phosphorescent organic LED (PHOLEDTM) pixel is LT70 55; 000h at an initial luminance of 1000cd/m2 for a 2mm2 pixel with 72lm/W efficacy and colorrendering index .CRI/ D 85.1 (Lumen, lm, is a measure of luminous flux. Candela, cd, is a measured of luminous intensity.) Although the lifetime of single-unit phosphorescent OLEDs is already extremely encouraging, here we describe an approach to further enhance device lifetime by stacking OLEDs so that light from two stacks can be combined without any need to increase the area of the light source. In this stacked OLED (SOLED) configuration, we separate emissive units by a charge-generation layer (CGL) that serves as an anode for one unit and as a cathode for a second unit.2, 3 SOLEDs offer longer operational lifetime than equivalent single-unit OLEDs because the required luminance from each unit is reduced for a given total light output. For example, where we have two units in a SOLED stack, each need Figure 1. Blue/red-green (B/RG) stacked organic LED (SOLED) architecture (device 1: left), red-green-blue/red-green-blue (RGB/RGB) SOLED architecture (device 2: right). BL: Blocking layer. CGL: Charge-generation layer. EML: Emission layer. ETL: Electron transport layer. HIL: Hole (positive charge carrier) injection layer. HTL: Hole transport layer. ITO: Indium tin oxide.