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Low-cost, Ultra-efficient Light Extraction Mechanism for Organic Light-Emitting Devices (OLEDs)

标题

Inkjet Printing of Microlenses for Photonic Applications

详细技术说明

None

*Abstract

Reduces Energy Consumption Allowing the OLEDs to Last Four Times Longer

This technology enhances the efficiency and longevity of organic light emitting devices (OLEDs) for both lighting and display applications. Although the internal efficiency of some high-quality OLEDs can be close to 100 percent, normally only about 20 percent of the light generated in an OLED can escape the device in the forward viewing directions. Various methods have been invented to enhance the light extraction efficiencies, which generally lead to 30 to 40 percent of the light escaping the device. The technology described here can potentially lead to the extraction of up to 80 percent of all the light generated in an OLED, more than doubling the efficiencies of the current methods. This light extraction mechanism can be manufactured using high throughput and low cost printing methods, and can be attached with little or no damage to an existing OLED device. In addition, there is no effect on the internal electrical performance levels of the device. This increased efficiency can be applied to any monochromatic emission device, full-color display, or white-light-emitting OLED used as solid-state lighting sources. This technique can also be combined with thin-film encapsulation methods to further prolong the lifetime of the OLEDs.

Application

A technique which can be universally applied to OLEDs of all colors to increase the overall device efficiency and lifetime by achieving a four-fold increase in the light extraction efficiency, which is more than doubled over the existing light extraction methods.

Advantages

• OLEDs can maintain the same level of luminance at much lower voltage and current levels, significantly reducing the energy consumption and operation costs
• Reduced energy needs increases lifespan of OLEDs by more than four times, making these devices more cost-effective and affordable in long-term projections
• A four-fold increase in light extraction efficiency does not affect internal efficiency, allowing the OLED to maintain extremely high internal efficiency levels while simultaneously improving external efficiency
• This light extraction mechanism can be included in current manufacturing processes, saving time and money by utilizing existing device fabrication techniques
• Decreased energy consumption significantly decreases the environmental impact of owning and operating OLEDs, a benefit for conscious consumers and businesses

Technology

Light generated by the organic emissive region of OLEDs can be emitted in (i) external modes, which can escape through the substrate in the forward viewing direction, (ii) substrate-waveguiding modes, which extend from the substrate/air interface to the metal cathode; and (iii) organic-waveguiding modes, which are confined within the high-refractive-index organic layers. The conventional planar-type OLEDs allow approximately 20 percent of all the light emission generated in an OLED to escape through the external modes, creating a very low light extraction efficiency of 20 percent. Various optical designs have been patented and/or reported, which may increase the light extraction efficiency to 30 to 40 percent, corresponding to a 50 to 100 percent increase. This technology incorporates a novel optical design to efficiently extract all waveguiding modes in an OLED, and can potentially lead to light extraction efficiencies up to 80%. The fabrication of this light extraction enhancement mechanism is compatible with existing high throughput, low-cost printing technologies, and will not noticeably change the electrical performance of the original OLED device. Unlike many existing methods, this technology will not change the emission spectrum, nor will it significantly alter the angular emission pattern. Therefore it can easily be incorporated into existing full-color displays or white-light-emitting devices without modifying the driving electronics. Resolutions as good as 20 microns can be achieved, making this technology suitable for monochromatic or full-color displays.

*IP Issue Date

Oct 18, 2011

*IP Publication Date

Jul 22, 2010

*Principal Investigation

Name: Elliot Douglas

Department:

Name: Jiangeng Xue

Department:

主要类别

化工/材料

细分类别

化工/材料应用

申请日期

Dec 16, 2009

申请号码

8,040,058

其他

国家/地区

美国