FAQ - Frequently asked questions.

What are the limitations on available OLED sizes and shapes?

The main limiting factor in terms of available sizes is the dimension of the OLED-substrate that can be manufactured within a certain production line. The maximum OLED-panel size will, however, always be smaller than the size of the substrate due to the nature of the production process. The largest panel currently available is the LG Display 320x320mm.

As all major OLED lighting manufacturers are currently using a Gen 2 fab (or smaller), panels larger than the 320x320mm produced by LG Display are only likely to appear once higher generation fabs are in operation. (Potentially after 2017)

In terms of shapes, theoretically any shape and size within the current substrate format is possible. Manufacturers may, however, be reluctant to offer customized versions as any new form entails large investment. Generally, we recommend choosing from the currently available range of different OLED-panel shapes and sizes and if possible tailoring the end application towards the standard panel sizes. For large volumes and in specific cases, customized versions are possible; please contact Organic Lights Technical Support for further information.

Will brighter OLED panels be available soon?

OLEDs have received some criticism of not being bright enough and that they are therefore not fit for general lighting applications. There are however two main reasons why we think that this is no longer the case and do recommend that people should try for themselves with the latest OLED panel generation:

  1. There have been tremendous technological improvements in terms of lifetime and luminous efficacy in recent years and all major manufacturers have ambitious technology targets until 2020. For more details on the relationship between lifetime and brightness, please check our Glossary.
  2. 2. As OLEDs can and should be used in different ways than LEDs or other traditional light sources, brightness should be compared on an application level. Why? As OLEDs act as a natural diffuser and do not produce glare, their light does not need to be covered with external lenses, shades or diffusers as it can be looked at directly by the human eye. Comparing OLEDs on an application level (i.e. LG Display's desktop lamp Sky) shows that the gap between other technologies is much smaller than many think.

Additionally, high brightness is not always the most important criteria and we strongly believe that OLEDs offer huge design advantages to justify using a product that has the best technology available today.

Can the brightness of an OLED panel be increased?

Yes. For all LG Display panels, it is possible to increase brightness from 3000 cd/m2 (standard rating) to up to 5000 cd/m2 by adjusting the input current.

See also: Glossary Lifetime

Will the price of OLEDs decrease significantly in future?

OLED prices are directly linked to the production capacity in operation. An upgrade from Gen 2 to Gen 5 production line (as planned by LG Display) will enable the manufacturer to more than triple the size of the substrate and hence reduce the costs at a similar rate. Additionally, a lot of research is currently being carried out worldwide to improve efficiencies within the different manufacturing steps and it can be expected that a fab upgrade would also mean an upgrade in production equipment. Analysts claim that a Gen 5 fab could achieve cost reductions of 70-90% compared to the current price level from Gen 2 fabs.

What is required to power an OLED panel?

OLED lighting panels generally require constant current. This can be achieved by using a constant current power supply or alternatively by integrating an OLED driver. The important element here is to limit the current the OLED can draw in order to avoid defects. We also recommended using a PWM dimmer to regulate the brightness of the panel.

OLEDs can be operated in series and parallel connection. A parallel connection will require an OLED driver whereas a series connection can be completed with only a constant current power source.

If a constant voltage power supply is preferred for mains connection, an OLED driver needs to be integrated in order to limit the current drawn by the panel.

For further information, please contact our Technical Support.

Is colour binning available for OLED panels?

For many applications, OLEDs will not be used in large arrays (unlike almost all LED lighting applications), which is why binning is generally less important. To guarantee a uniform appearance however, manufacturers tend to offer fairly close binning by default. LG Display for instance guarantees that all panels will be supplied within a range of 4-steps MacAdam. A narrower selection is available on request; please contact Technical Support for further details.

See also: Glossary on binning and MacAdam Elipse

How does the CRI change over different currents?

As with any LED, there will be a slight colour shift with increasing currents. In the case of OLEDs, a slightly higher colour temperature can be expected. The impact on the CRI has not yet been tested; LG Display will include this into their testing procedures.

Can an array of panels be assembled without a visible space between them?

At the current state of technology, it is necessary to keep a small frame (sometimes referred to as bezel) around the illuminated part of the OLED panel.

Are OLED panels suitable for outdoor usage?

Outdoor usage is currently not recommended due to several factors:

  • High/low temperature
    The manual specifies operating tests in harsh conditions, however, tests are only carried out for 96 hours. After this time, tests panels are functional but LG Chem is not able to guarantee long-term working ability in such conditions. Different temperatures also cause changes of the electrical parameters of the OLEDs like resistivity for instance, which can cause higher current flow and therefore affects lifetime.
  • Humidity
    OLEDs are quite sensitive to humidity and are protected by special encapsulation. However, it is not recommended exposing OLEDs to humidity for longer periods of time.
  • UV
    There are two reasons why UV is important. Firstly, organic material cannot be exposed to UV radiation for too long because of degradation.
    The second aspect is that encapsulation can degrade due to UV exposure, which can affect humidity exposure. Degradation will result in a drop in luminous flux.

Summary: To use OLEDs outdoors, the panels have to be sealed in IP protected housing. Additionally, UV and temperature differences should be carefully considered.

Is screen-printing possible?

Yes. This option is particularly valuable for Emergency Light (EL) panels and we have received very positive feedback from customers who have already trialled it successfully. The recommended printing method on the panel is screen printing.

What force can be applied to the panel?

LG Display performed a test with a pointer (<500µm) with following results:

Encapsulation side: The panel was torn at press point at 190N. However, even at 10N dark spots occurred at the point where the pressure was applied.

Active side: Dark spots occurred at pressure point at 50N. No mechanical damage below 30N.

Conclusion: Small pointy edges should be avoided on the surface where the panel is mounted to avoid dark spots. If pressure is applied over a wider area (i.e. the width of the panel), much larger forces can be sustained.

Do the panels have any special handling requirements to be considered?

It is extremely important not to put direct pressure on the panel surface during assembly i.e. pressing the panels into a frame or holder. Direct pressure can harm the organic layers and cause dark spots with direct impacts on the visual experience.

Please consider the Handling Instructions for further detail.

How can the panels be cleaned?

Cleaning is very important, especially when the panels are used in commercial lighting applications. Standard commercial IPA cleaners can be used with excellent results. Materials that react aggressively to plastic should be avoided e.g. solvents.

Is it possible to manufacture panels with different colours/ colour temperatures?

Generally yes. For example, some emergency lighting manufactures insist on colour temperatures >6000K. Signmakers may be interested in using different colours, i.e. red or blue.

As OLEDs are an RGB-light source, there is theoretically a lot of colour variety possible. However, not all colours would retain the same brightness and lifetime. This is one of the big challenges for OLED manufacturers seeking to improve the efficiency of the blue emitters.

Although variations are possible, they can incur costly changes to the manufacturing process.

If you wish to discuss alternatives in shape, colour etc., please contact us directly and we will be happy to advise you.

Is it possible to incorporate dynamic elements into the panel i.e. a moving arrow for signs?

From a technological point of view, adaptation of dynamic elements is possible. If you wish to discuss this further, please contact us directly and we will be happy to advise you.

Are transparent OLEDs available yet?

Transparent OLEDs that can be incorporated into windows for instance have long been discussed and a lot of research has been carried out. However, there are currently no commercially available products on the market.

Is it foreseen to have OLED panels with spring contacts to improve handling?

Spring contacts can put additional stress on the panel and therefore soldering pads are preferred. LG Display is currently developing module solutions with easy connect contact clips to increase the possible uses of OLED panels in lighting applications.