UV block for
OLED displays

OLED displays increase brilliance and provide a true black color. As our automotive partners incorporate them into increasingly complex display stacks, they are looking for methods to reduce the total number of steps in the production process. 

Together with colleagues, Prof. Blankenbach investigated the effects of UV damage on displays. They concluded that displays in demanding applications like automotive and digital signage need UV protection to increase lifespan.  

At tesa we have taken this work further, combining it with the feedback of our customers to produce an optically clear adhesive with UV blocking properties. This OCA protects itself and the layers behind against the harmful impact of UV exposure. It means additional UV protection layers such as polarizers are no longer required. 

The effects of UV protection on OLED displays

Electronic displays require protection from UV light. That is because, over time, UV light destroys organic materials in OLEDs and inorganic materials such as plastics in LCDs, microLEDs and OLEDs, and decreases their performance.

Testing on OLED displays with 500 hours of UV light exposure reveals that luminance decreases by less than one per cent when UV protection is applied, compared to a fall of 5 % in unprotected OLEDs. At a lower luminance, readability in bright light decreases on OLED displays, while a degraded polarizer reduces the contrast for LCDs. Therefore, when integrating displays into cars a proper UV light blocker is required to ensure its long term and high-quality use. The key challenge for engineers designing the optical display stack is finding the balance between effective UV light blocking and a very high transmission of visible light.  

With some changes to the structure of the display design, we believe we can give engineers that flexibility.  

Integrating the UV block into the optically clear adhesive means there is no need for additional UV blocking layers such as coatings on polarizers. This in turn leads to a reduction of the total number of steps in the production process. 

Furthermore, engineers prefer the blocking function to be the closest to the front lens. This offers secure protection for the OCA itself and all layers behind it – such as polarizers, touch sensors and especially sensitive OLED components – against harmful UV radiation.  

With these requirements met, engineers can focus on new trends and make new designs such as curved or narrow frame displays happen. 

The UV blocker has been designed not to obscure visible light from being transmitted to the OCA, and block UV light. In fact, testing showed over 99 % of visible light transmissions passing through.

It means high brightness with hardly any loss due to the special UV protection integrated into the OCA. 

Reliability tests such as lifetime and thermal stress were carefully set up to ensure the accuracy of the tape’s performance – all of which were passed successfully.  

Under stringent testing conditions, our tesa® OCA 88910 has demonstrated its ability to block UV radiation while transmitting the relevant visible light, making it a valuable display component to an automotive industry that is always looking for ways to innovate. 

This piece was written in collaboration with Prof. Karlheinz Blankenbach, founder of the Display Lab at Pforzheim University.