Wednesday 3 November 2021
High Efficiency Deep Blue OLEDs
Seoul National University, Korea
Time: 1pm in QLD 2pm in NSW, ACT, Vic, and Tas
11am in WA
12:30pm in NT
1:30pm in SA
4pm in New Zealand
Meeting URL: https://jcu.zoom.us/j/83099059507
The efficiency of organic light emitting diodes has been significantly improved during the last several years by developing phosphorescent and TADF emitters with high horizontal emitting dipole orientation and high PLQY along with the development of device structure with excellent charge balance to get EQE reaching almost 40%, corresponding to almost the theoretical limit of the efficiency. The most important remaining issue is the development of deep blue OLEDs. In this talk, we will firstly present a theoretical model to analyze the degradation mechanism of OLEDs and application of the model to blue OLEDs. Then we will talk about a strategy to realize deep blue TADF OLEDs with the EQE of 28% and CIE y value of 0.09 by narrowing the emission spectrum of blue emitting TADF emitters along with high horizontal emitting dipole orientation. Lastly, we will discuss on deep blue OLEDs utilizing triplet-triplet annihilation (TTA) process based on anthracene derivatives. For blue-emitting anthracene derivatives, the theoretical maximum contribution of TTA to emissive singlet excitons is 15%, which is insufficient for high-efficiency fluorescent devices. In this study, we realised a TTA contribution of nearly 25% using an anthracene derivative, breaking the theoretical limit. As a result, efficient deep-blue TTA fluorescent devices were developed, which exhibited maximum external quantum efficiencies of 10.2%. A theoretical model will be presented to explain the experimental results considering both the TTA and RISC to a singlet state from a high level triplet state formed by the TTA process.
During the seminar:
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Please be aware that the talks will be recorded and posted on the AUCAOS website.
Previous seminars can be viewed here: https://seminars.aucaos.org.au/
Call for abstracts:
Seminars are typically held on the first Wednesday of each month.
At this time we are specifically encouraging HDR students to present their work to broad audience. If you are interested in speaking then please submit an abstract to firstname.lastname@example.org.