Intramolecular Cyclization: A Convenient Strategy to Realize Efficient BT.2020 Blue Multi‐Resonance Emitter for Organic Light‐Emitting Diodes

Abstract

Rationally tuning the emission position and narrowing the full width at half-maximum (FWHM) of an emitter is of great importance for many applications. By synergistically improving rigidity, strengthening the resonant strength, inhibiting molecular bending and rocking, and destabilizing the HOMO energy level, a deep-blue emitter (CZ2CO) with a peak wavelength of 440 nm and an ultranarrow spectral FWHM of 16 nm (0.10 eV) was developed via intramolecular cyclization in a carbonyl/N resonant core (QAO). The dominant υ 0-0 transition character of CZ2CO gives a Commission Internationale de I'Éclairage coordinates (CIE) of (0.144, 0.042), nicely complying with the BT.2020 standard. Moreover, a hyper-fluorescent device based on CZ2CO shows a high maximum external quantum efficiency (EQE max ) of 25.6 % and maintains an EQE of 22.4 % at a practical brightness of 1000 cd m À 2 .

Novel π-Extended Indolocarbazole-Based Deep-Blue Fluorescent Emitter with Remarkably Narrow Bandwidth for Solution-Processed Organic Light-Emitting Diodes

“…Both 4 t Cz-DICz and 4Hex-DICz in toluene exhibit very narrow PL emissions at 422 and 423 nm with bandwidths of 16 and 18 nm, respectively. Such narrow emission bandwidths can be attributed to the rigid structure of the DICz core with relatively little change in charge distribution upon electronic emission. , Additionally, in toluene, both 4 t Cz-DICz and 4Hex-DICz exhibit minimal Stokes shifts of 9 and 10 nm, respectively. These can be attributed to the rigid structure of the DICz core, which undergoes relatively little change in the charge distribution during electronic emission.…”

Homoleptic purine-based NHC iridium(iii) complexes for blue OLED application: impact of isomerism on photophysical properties

“…For iridium(III) complexes PL band broadening is indicative of a greater deviation between ground (S 0 ) and excited triplet (T 1 ) state geometries and suggests increased conformational uncertainty of the corresponding structures. 41,42 To support this assumption time-wavelength resolved maps of mer-PhP emission for TOL solution covering the first 50 ns after excitation was obtained at room temperature and at 77 K (Fig. 4).…”

Recent progress and prospects of fluorescent materials based on narrow emission

“…4w), via intramolecular cyclization in a N/CO resonant core ( QAO ). 58 Compared to QAO , CZCO and CZ2CO exhibited blueshifted emissions at 430 and 440 nm with FWHMs of 32 and 16 nm, respectively. The Δ E ST /PLQY values were estimated to be 0.33 eV/75% for CZCO and 0.34 eV/84% for CZ2CO .…”

“…4 (a-y) Chemical structures of emitters discussed in Section 3.1.1. 26,[32][33][34][38][39][40][41][42][43][44][47][48][49][50][51][52][53][54][55][56][57][58][59] This journal is © The Royal Society of Chemistry 2023…”