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Attaining phosphorescent materials with narrowband emission is crucial for advancing wide‐color‐gamut organic light‐emitting diode (OLED). Herein, a rigid modification strategy is introduced for iridium(III) complexes to achieve the narrowband red emission with negligible 0–1 peak. By introducing the rigid indolo[3,2,1‐jk]carbazole (ICz) into the cyclometalated ligand, Ir(III) complexes, ICziq‐Ir and ICzqz‐Ir, exhibit pure red phosphorescence with emission peaks at 608 and 613 nm and full widths at half‐maximum (FWHMs) of 37 and 38 nm (0.12 and 0.13 eV) in toluene, respectively. Furthermore, the specific site modification of ICzqz‐Ir greatly suppresses the high‐frequency vibration of the structure, resulting in the narrowband photoluminescent spectrum close to the Gaussian distribution with superior color purity. The OLEDs utilizing ICziq‐Ir and ICzqz‐Ir demonstrate maximum external quantum efficiencies of 21.4 and 17.8% as well as mild efficiency roll‐off. Remarkably, the electroluminescence spectra exhibit similar narrowband red emission with FWHMs of 37 and 43 nm and CIE coordinates of (0.65, 0.35) and (0.66, 0.34), attesting to the excellent color purity of the phosphorescent OLEDs. [ABSTRACT FROM AUTHOR]

Recent development of most organic long persistent luminescence (OLPL) systems employed binary or tertiary doping. However, the design strategies towards OLPL materials with hour‐long afterglow duration are still quite limited. Here, we propose a novel OLPL system through melt‐casting method with 0.1 mol % of CuI complexes: 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl BINAP‐CuX (X=Cl, Br and I) doped into the triphenylphosphine (TPP) host. The charge separation was initiated prior to excitation through host coordination with CuI complexes, resulting in semi‐free halogen ions and in situ generated CuI cations, which forms TPP + BINAP‐CuX ionic pairs and subsequently ionic solids. The OLPL lifetime can be readily modulated by different halogen atoms and the afterglow can last up to more than 3 hours perceivable to human eyes. This is a rare example of OLPL initiated through host‐guest coordination that could potentially expand the definition of OLPL systems and design strategies. [ABSTRACT FROM AUTHOR]

The integration of carbazole (Cz) unit and emissive iridium(III) complexes is a wise choice to facilitate hole injection/transport, charge balance, and achieve phosphorescent emitters for high‐performance organic light‐emitting diodes (OLEDs). Herein, three efficient Cz‐based Ir(III) complexes are synthesized and applied for OLEDs. The introduction of trifluoromethyl and trimethylsilyl units alter the photoelectric properties of these complexes, achieving photoluminescence (PL) from yellow (559 nm) to orange‐red (600 nm) with high PL quantum yields between 75% and 93% and short excited state lifetimes between 1.09 and 1.90 µs in doped thin films. Multilayer OLEDs using the three emitters exhibit highest current efficiency as high as 100.4 cd A−1 and maximum external quantum efficiency (EQEmax) up to 32.2% with very low efficiency roll‐off. Even at high brightness of 5000 and 10 000 cd m−2, the device D3 still can maintain the EQE at 28.2% and 27.9%, respectively. These results indicate that these complexes incorporating Cz units are potential substituents for efficient OLEDs. [ABSTRACT FROM AUTHOR]

Pure organic materials with intrinsic room‐temperature phosphorescence typically rely on heavy atoms or heteroatoms. Two different strategies towards constructing organic room‐temperature phosphorescence (RTP) species based upon the through‐space charge transfer (TSCT) unit of [2.2]paracyclophane (PCP) were demonstrated. Materials with bromine atoms, PCP‐BrCz and PPCP‐BrCz, exhibit RTP lifetime of around 100 ms. Modulating the PCP core with non‐halogen‐containing electron‐withdrawing units, PCP‐TNTCz and PCP‐PyCNCz, successfully elongate the RTP lifetime to 313.59 and 528.00 ms, respectively, the afterglow of which is visible for several seconds under ambient conditions. The PCP‐TNTCz and PCP‐PyCNCz enantiomers display excellent circular polarized luminescence with dissymmetry factors as high as −1.2×10−2 in toluene solutions, and decent RTP lifetime of around 300 ms for PCP‐TNTCz enantiomers in crystalline state. [ABSTRACT FROM AUTHOR]