The low efficiency of fluorescent blue OLED pixels remains one of the top issues for OLED panel makers despite the success that OLED displays have had on the market in the last decade. Recent progress on the TADF technology, however, has shown this technology´s potential to finally deliver high-efficiency deep-blue materials that also have enough stability for OLED panels. CYNORA has already shown that the customer specifications for color and efficiency can be reached and the lifetime is in the final development stage. We were able to reach these results with two separate TADF approaches, the self-emitting and the co-emitting (or hyper) approach. In this paper, we will show some of the requirements for the TADF emitter that are necessary to achieve good results in the co-emitting approach. We will discuss the theoretical requirements to achieve good energy transfer from a TADF emitter to a fluorescent emitter. We will also show device results that confirm the required deep-blue color of the TADF emitter for efficient hyper-fluorescent devices. And we will also give an update on our latest results where we have achieved more than 20% EQE (external quantum efficiency) at deep-blue colors with a CIEy 1931 coordinate of ≤0.15.
The mobile display market is strongly shifting towards AMOLED technology which enables curved and
flexible displays. Therefore, the demand for highly efficient OLED emitters to reduce power
consumption and increase display resolution at the same time is growing. There are efficient green and
red OLED emitters in mass production already, but there is no efficient blue counterpart.
CYNORA´s approach to provide efficient blue OLED emitters is based on thermally activated delayed
fluorescence technology. TADF emitter systems allow for an efficiency increase of up to four times
compared to conventional fluorescent systems by utilizing both triplet and singlet excitons for the
emission of light. At the same time, they maintain deep blue emission, i.e. CIEy < 0.2.
Herein, we review our recent progress on TADF emitters, reaching 20% EQE at 1000 nits in deep blue
OLED devices (< 460 nm peak wavelength) together with reasonable LT97 values. The performance of
these new blue TADF emitters is now in the range of commercial requirements for blue emitters in
OLED displays.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.