Improving lifetime of high‐efficiency blue OLED based on thermally activated sensitized fluorescence

Abstract

As a promising technology toward high-efficiency organic light-emitting diode (OLED), thermally activated sensitized fluorescence (TASF) has encountered major obstacles toward achieving sufficient operational lifetime when it comes to deep blue emission that is desirable for display applications. We have systematically investigated various factors affecting TASF OLED stability and successfully improved device lifetime by using a thermally activated delayed fluorescence (TADF) sensitizer with a fast reverse intersystem crossing rate (k RISC ).

High efficiency and high color purity deep‐blue organic light‐emitting diodes with blue index >500

“…12 Apparently, fast FRET process can effectively reduce triplet exciton concentration, suppress triplet exciton annihilations, alleviate efficiency roll-off at high brightness, and ensure a high efficiency for sensitized OLEDs. [13][14][15] Besides, favorable terminal fluorescent emitter is required with narrow FWHM for outstanding color purity. 16 In our study, a deep-blue phosphorescent material was involved as sensitizer for narrow FWHM blue fluorescent emitter.…”

“…A key factor influencing the performance of sensitized OLEDs is Förster resonance energy transfer (FRET) 12 . Apparently, fast FRET process can effectively reduce triplet exciton concentration, suppress triplet exciton annihilations, alleviate efficiency roll‐off at high brightness, and ensure a high efficiency for sensitized OLEDs 13–15 . Besides, favorable terminal fluorescent emitter is required with narrow FWHM for outstanding color purity 16 …”