Multi‐Resonance Induced Thermally Activated Delayed Fluorophores for Narrowband Green OLEDs

Abstract

High-color-purity emissions with small af ull-width at half-maximum (FWHM) are an ongoing pursuit for highresolution displays.T hough the flourishment of narrow-band emissive materials with multi-resonance induced thermally activated delayed fluorescence (MR-TADF) in the blue region, such materials have not validated their potential in other color regions.Byamplifying the influence of skeleton and peripheral units,as eries of highly efficient green-emitting MR-TADF materials are firstly reported. Peripheral units with electrondeficit properties can significantly narrowt he energy gap for bathochromic emission without compromising the color fidelity.MR-TADF emitters with photo-luminance quantum yields of above9 0% with FWHMs of 25 nm are developed. The corresponding organic light-emitting diodes showm aximum external quantum efficiency/ power efficiency of 22.02 %/ 69.82 lm W À1 with excellent long-term stability.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Strategically Modulating Carriers and Excitons for Efficient and Stable Ultrapure‐Green Fluorescent OLEDs with a Sterically Hindered BODIPY Dopant

“…It is worth noting that, though few TADF‐OLEDs with similar CIEs showed relatively higher EQE max , device D2 showed the state‐of‐the‐art performances with brightness >1000 cd m −2 , which is more adequate for practical applications, testifying the great potential of TSF‐OLEDs for narrow‐band emission. [ 26,6b ] Besides, arising from the adoption of TADF host in favor of low voltages, the highest PE max was observed for D2 among all devices summarized.…”

The design of an extended multiple resonance TADF emitter based on a polycyclic amine/carbonyl system

“…To the best of our knowledge, there exists only a single report of green MR-TADF OLEDs with l EL ranging from 493-501 nm and EQE max ranging from 21-22%. 22 The results demonstrate how to design MR-TADF emitters exhibiting both a red-shifting of the emission and a suppression of concentration quenching in the solid state.…”

Molecular‐Structure and Device‐Configuration Optimizations toward Highly Efficient Green Electroluminescence with Narrowband Emission and High Color Purity

“…Importantly, the EQE maintains a high value of 20.1% at practical high luminance of 1000 cd m −2 . Compared with a very recently reported high‐performance narrowband green OLED based on a MR‐TADF material (FWHM: 39 nm; CIE: (0.20, 0.58); EQE: 21.0% at 1000 cd m −2 ), [ 12 ] our device with 2 wt% doping concentration features a narrower EL band and a better color purity while maintaining a very close EQE at practical high luminance, although the efficiency of the device is still not comparable to those of some ultraefficient green devices with EQE max over 30%. [ 32b,33 ] To improve the purity for green emission and EQE, the molecular structure modification and device configuration optimization will be performed in the future.…”

“…Very recently, Zhang et al reported several green MR‐TADF compounds, which exhibit narrowband EL (FWHM: 32–40 nm) with high EQE max (20.9–22.7%), but the best CIE coordinates of (0.20, 0.58) largely deviated from the NTSC standard (CIE: (0.21, 0.71)). [ 12 ] So far, the development of efficient narrowband green emitters that can achieve pure green EL with the CIE coordinates that approach the mainstream NTSC standard remains an unaddressed issue.…”

“…To the best of our knowledge, such high green‐light color purity is among the best results ever achieved by TADF materials. [ 12,32 ] Meanwhile, extremely narrow EL band (FWHM: 33 nm) is maintained. Moreover, 2 wt% doping concentration also provides a quite low V on of 2.6 V, and fairly high L max , CE max , PE max , and EQE max of 38 480 cd m −2 , 76.0 cd A −1 , 89.6 lm W −1 , and 25.5%, respectively.…”