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The solubility of luminescent materials is a key parameter to improve the electroluminescent performances of solution-processed organic light-emitting diodes (OLEDs). The through-space charge transfer (TSCT) materials provide an alternative to introduce the solubilizing groups (SGs) to the linker. Herein, the tert-butyl and n-hexyl groups are introduced as SGs at C7 positions of spiro structure, named C6-DMB and tBu-DMB, away from the acceptor. This has no influence on the photophysical properties of the parent TSCT molecule. Highly efficient solution-processed OLEDs were demonstrated with the maximum external quantum efficiencies of 21.0% and 21.7%, respectively. To the best of our knowledge, these are champions in the state-of-the-art solution-processed OLEDs with TSCT emitters. This work confirmed our conjecture of constructing highly efficient soluble emitters by transforming an outstanding TSCT material from thermal evaporation to solution-processed OLEDs with SGs simply integrated on the 'bridge' linker. [ABSTRACT FROM AUTHOR]

Multi‐layer π‐stacked emitters based on spatially confined donor/acceptor/donor (D/A/D) patterns have been developed to achieve high‐efficiency thermally activated delayed fluorescence (TADF). In this case, dual donor moieties and a single acceptor moiety are introduced to form two three‐dimensional (3D) emitters, DM‐BD1 and DM‐BD2, which rely on spatial charge transfer (CT). Owing to the enforced face‐to‐face D/A/D pattern, effective CT interactions are realized, which lead to high photoluminescence quantum yields (PLQYs) of 94.2 % and 92.8 % for the two molecules, respectively. The resulting emitters exhibit small singlet–triplet energy splitting (ΔEST) and fast reverse intersystem crossing (RISC) processes. Maximum external quantum efficiencies (EQEs) of 28.0 % and 26.6 % were realized for devices based on DM‐BD1 and DM‐BD2, respectively, which are higher than those of their D/A‐type analogues. [ABSTRACT FROM AUTHOR]

The development of red/near-infrared (NIR) thermally activated delayed fluorescence (TADF) emitters are relatively lagging due to the spin statistics and energy gap law. Herein, we designed and synthesized a new NIR TADF emitter, 3-(4-(9,9′-spirobi[fluorene]-3-yl(phenyl)amino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarboni-trile (SDPA-APDC) , by incorporating a spiro-type electron-donating moiety N , N -diphenyl-9,9′-spirobi[fluorene]-2-amine (SDPA) to an electron-withdrawing unit acenaphtho[1,2- b ]pyrazine-8,9-dicarbonitrile (APDC). The photophysical, electrochemical and thermal properties of SDPA-APDC have been systematically explored. Consequently, the emitter was found high photoluminescence quantum yield (PLQY), narrow bandgap, small singlet-triplet energy gap (Δ E ST) and excellent thermal stability. Furthermore, SDPA-APDC was developed for electroluminescence devices. The doped devices of SDPA-APDC achieved a red emission peak at 696 nm with a maximum external quantum efficiency (EQE) of 10.75%. And the non-doped device exhibited a NIR emission peak at 782 nm with a maximum EQE of 2.55% Image 1 • Designing a near-infrared TADF emitter SDPA-APDC. • The doped and non-doped OLEDs of SDPA-APDC exhibited a maximum external quantum efficiency (EQE) of 10.75% (red emission peak at 696 nm) and 2.55% (NIR emission peak at 782 nm), respectively. • Enriching the design principles of efficient red/NIR TADF emitters based on more different electron donors. [ABSTRACT FROM AUTHOR]

Deep‐red and near‐infrared emitters with twisted donor–acceptor (D–A) structures often exhibit suboptimal performance in organic light‐emitting diodes (OLEDs) due to constraints imposed by the energy gap law. In this work, a pure hydrogen carbon (PHC) host material named SBF‐DTP is purposefully tailored for deep‐red OLEDs. The excellent capacity of SBF‐DTP to support D–A type DR emitters effectively arises from its distinctive attributes: localized excitation states, 3D configuration, and low polarity. When employing SBF‐DTP as the host for the fluorescence emitter DCPA‐TPA and the thermally activated delayed fluorescence emitter APDC‐DTPA, doped films exhibit substantially enhanced photoluminescence quantum yields. This improvement leads to high‐efficiency OLEDs with external quantum efficiencies of 5.47% for DCPA‐TPA and 20.03% for APDC‐DTPA, respectively, which is about twice as high as the initial reports. This findings underscore the paramount significance of developing efficient host materials in the pursuit of high‐performance deep red and even near‐infrared OLEDs. [ABSTRACT FROM AUTHOR]