High Efficiency of over 25% and Long Device Lifetime of over 500 h at 1000 nit in Blue Fluorescent Organic Light‐Emitting Diodes

Abstract

In this study, a multiple resonance (MR) type blue emitter is synthesized, characterized, and evaluated for highly efficient and stable blue fluorescent organic light‐emitting diodes (OLEDs). The MR blue fluorescent emitter has a di‐tert‐butyl benzene substituent in the MR core structure to minimize quenching mechanisms by intermolecular interaction. The emitter shows a high photoluminescence quantum yield and small full width at half maximum of 22 nm, which realize high external quantum efficiency (EQE) of 11.4% in the single unit OLED and device lifetime up to 95% of the initial luminance (LT95) of 208 h at 1000 cd m−2 and over 10 000 h at 100 cd m−2. The optimized tandem device of the new blue emitter achieves high EQE over 25% and extremely long LT95 of over 500 h at 1000 cd m−2 and 30 000 h at 100 cd m−2. The lifetime of this work is one of the best data of blue OLED lifetime reported in the literature.

Boron‐Based Narrowband Multiresonance Delayed Fluorescent Emitters for Organic Light‐Emitting Diodes

“…In 2022, Lee et al reported MR‐TADF blue emitter ( t‐DABNA‐dtB ) by introducing di‐tert‐butyl benzene substituent in the MR core ( t‐DABNA ) to minimize the quenching mechanisms by restricting the intermolecular interaction. [ 105 ] The designed emitter showed a high PLQY and small FWHM ≈ 22 nm, which realized high EQE of 11.4% in the single unit OLED with operational lifetime LT 95 of 208 h at 1000 cd m −2 and over 10 000 h at 100 cd m −2 . The t‐DABNA‐dtB displayed pure blue emission λ EL ≈ 470 nm with a CIEy coordinate of ≈0.13.…”

Fine-tuned asymmetric blue multiple resonance thermally activated delayed fluorescence emitters with high efficiency and narrow emission band

“…However, excimer emission or aggregated concentration quenching caused by intermolecular interaction are challenging hurdles due to planar structural characteristics. 18–22 Based on 5,9-diphenyl-5,9-diaza-13 b -boranaphtho[3,2,1- de ]anthracene (DABNA-1), various derivatives have been reported in which the emission wavelength and photophysical properties of materials are controlled. 23–33 For example, Wang and coworkers reported a t -butyl carbazole substituted emitter (DtBuCzB) instead of a diphenylamine modified one.…”

Molecular mechanism of rigidity- and planarity-promoted, state-dependent doping of conjugated ladder-type molecules

“…10,11 Doping is a common method for tuning and controlling the charge-carrier density in organic semiconductors (OSCs). The doping process is crucial for the functioning of organic light-emitting diodes, [12][13][14] organic field-effect transistors, 15,16 organic photovoltaics, 17 organic thermoelectrics, 18 etc. Consequently, a large number of studies on doping for conjugated organic materials have been carried out, resulting in exceptionally high electrical conductivity values that exceed 1000 S cm À1 .…”