Micro lenses make OLEDS more efficient
15 October 2008
Organic light emitting diodes (OLEDs) are optimistically being looked upon as the technology set to become disruptive in displays and lighting.
For this to happen however, there are challenges that need to be overcome, such as the efficiency and lifetime of OLEDs.
From the perspective of lighting applications, there are several initiatives being taken to make OLEDs more competitive with incandescent bulbs and fluorescent lights. A current problem with OLED-based lighting is that a major portion of white light is trapped within the device and only 20% of the light generated is released.
White light from OLEDs is created by applying a voltage across nanometre-thick layers of organic semiconductors that are sandwiched between a pair of electrodes. The applied voltage stimulates the material to emit light.
Suggesting improvements to the device design, researchers at the University of Michigan and Princeton University have demonstrated better efficiency by increasing the illumination released to 60%. Conventionally, the light is reflected internally along the surface of the semiconductor and not in the desired perpendicular direction. To overcome this problem, the researchers have introduced an organic grid along with micro lenses to direct the trapped light out of the OLED. The grids are used to refract the trapped light and guide it to the five micrometre thick dome-shaped lenses. The lenses emit the light in the vertical direction and help improve device efficiency.
This white OLED architecture is beneficial due to the fact that it can emit 70 lumens per watt of power, compared to the 15 lumens per watt of incandescent light bulbs. Despite the fact that fluorescent tubes still give out 90 lumens per watt, the quality of light from tube lights is harsh and could also make use of toxic substances such as mercury.
White OLEDS also have the advantage of being incorporated on to flexible substrates such as metal foils and plastic substrates. The constituent organic materials are carbon-based dyes akin to those in photographic prints and are economical.
The researchers aim to show further improvement by utilising OLEDs of higher efficiencies than those currently used in the project. The team remains optimistic about the scalable manufacturing of the technology and is convinced about the competitiveness of production costs.
The impact of adoption of such technologies in interior illumination could lead to a reduction in energy demand for lighting in buildings. While OLED technology would take a while to reach its disruptive potential, such developments could certainly accelerate the adoption of OLED lighting.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)21 680 3274, firstname.lastname@example.org, www.frost.com
Customisable industrial display
25 March 2020, Vepac Electronics
Topcon Positioning Group announces a pre-series release of its new OPUS B-Series display available for the developer, systems integrator and manufacturer market for user-interface design and implementation ...
Automotive LED drivers and controllers
29 January 2020, Future Electronics
ON Semiconductor has launched a new family of four devices that facilitate the high levels of performance and innovative functionality that vehicle manufacturers and consumers now expect from automotive ...
Photocouplers for industrial equipment and solar inverters
29 January 2020, Hi-Q Electronics
Renesas Electronics announced five new 8,2 mm creepage photocouplers that are the world’s smallest isolation devices for industrial automation equipment and solar inverters. With a package width of 2,5 mm, ...
Image sensor evaluation kits
25 November 2019, Future Electronics
Ams has released the NanoVision and NanoBerry evaluation kits, which provide a ready-made platform for the development of innovative solutions based on the ams NanEyeC miniature image sensor.
The NanEyeC ...
VentoFlex modular LED lighting system
23 October 2019, Mimic Components
Visual Communications Company (VCC) launched its VentoFlex flexible modular lighting system. The system is made up of flexible copper clad laminate (FCCL) sheets with 90 CRI Luxeon LEDs. VentoFlex was ...
LED flicker, and how to prevent it
28 August 2019, Avnet South Africa
With the growing popularity of LED lighting, especially now that very cheap LED luminaires are coming to the market, flicker is becoming more of a problem.
Flicker, a repetitive switching on and off ...
Digital fibre-optic sensor
28 August 2019, Vepac Electronics
The DFS digital fibre-optic sensor series from Tri-Tronics is designed to provide reliable detection using plastic fibre-optic light guides.
The slim-line housing with protective lid will fit in a variety ...
All-in-one light pipe system
28 August 2019, Vepac Electronics
Bivar’s Zero Light Bleed adaptor technology, with built-in surface-mount LED, channels light directly to the lens, eliminating disruptive light bleed.
The all-in-one adaptor system is built with optimum ...
High-intensity colour LEDs
31 July 2019, Würth Elektronik eiSos
Würth Elektronik has expanded its LED portfolio with a particularly compact model family. The WL-SMCC series of SMT chip LEDs, available in 0402 and 0603 packages, is characterised by a full-surface lens ...
RGB LEDs for decorative lighting
26 June 2019, Würth Elektronik eiSos
Würth Elektronik’s new WL-SFTW and WL-SFTD series of RGB LEDs are targeted at accent and decorative lighting, optical displays as well as industrial applications. Thanks to their PLCC contacting design, ...