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Circularly Polarized Luminescence from Chiral Conjugated Poly(carbazole-ran-acridine)s with Aggregation-Induced Emission and Delayed Fluorescence
摘要： Pure organic materials with circularly polarized luminescence (CPL) and delayed fluorescence have gained increasing interest from academic and technological areas. To enhance the solid-state emission and exciton utilization in chiral optoelectronic devices, a synthetic strategy to impart conjugated polymers with CPL and aggregation-induced delayed fluorescence was proposed. Herein, two conjugated macromolecules with electron-donating poly(carbazole-ran-acridine) backbones, electron-withdrawing dibenzothiophen-2-yl(phenyl)methanone and chiral alanine moieties were designed and synthesized. Their neat films exhibited strong green emission with quantum yields of 6.7% and 10.3% and delayed fluorescence with lifetime of 1.358 μs and 1.366 μs, respectively. Both Cotton effect and CPL with dissymmetry factor of –2.01 × 10–3 and –1.39 × 10–3 were determined in the solid state. Such unique conjugated polymers were employed as solution-processed emitting layers in organic light emitting diodes, which displayed maximum brightness of 1477 cd/m2 and maximum current efficiency of 2.52 cd/A.
关键词： OLEDs,conjugated polymers,aggregation-induced emission,delayed fluorescence,aggregation-induced delayed fluorescence,circularly polarized luminescence
更新于2025-09-23 15:23:52
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Hydrophilic, Red-Emitting, and Thermally Activated Delayed Fluorescence Emitter for Time-Resolved Luminescence Imaging by Mitochondrion-Induced Aggregation in Living Cells
摘要： Thermally activated delayed fluorescence (TADF) materials have provided new strategies for time-resolved luminescence imaging (TRLI); however, the development of hydrophilic TADF luminophores for specific imaging in cells remains a substantial challenge. In this study, a mitochondria-induced aggregation strategy for TRLI is proposed with the design and utilization of the hydrophilic TADF luminophore ((10-(1,3-dioxo-2-phenyl-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)-9,9-dimethyl-9,10-dihydroacridin-2-yl)methyl)triphenylphosphonium bromide (NID-TPP). Using a nonconjugated linker to introduce a triphenylphosphonium (TPP+) group into the 6-(9,9-dimethylacridin-10(9H)-yl)-2-phenyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (NID) TADF luminophore preserves the TADF emission of NID-TPP. NID-TPP shows clear aggregation-induced delayed fluorescence enhancement behavior, which provides a practical strategy for long-lived delayed fluorescence emission in an oxygen-containing environment. Finally, the designed mitochondrion-targeting TPP+ group in NID-TPP induces the adequate accumulation of NID-TPP and results in the first reported TADF-based time-resolved luminescence imaging and two-photon imaging of mitochondria in living cells.
关键词： time-resolved luminescence imaging,aggregation-induced delayed fluorescence enhancement,thermally activated delayed fluorescence,mitochondria-specific imaging
更新于2025-09-23 15:22:29
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Aggregation-Induced Delayed Fluorescence Luminogens with Accelerated Reverse Intersystem Crossing for High-Performance OLEDs
摘要： A fast reverse intersystem crossing (RISC) is of high importance for delayed fluorescence emitters in terms of increasing exciton utilization and suppressing efficiency roll-off. Herein, new robust luminogens comprised of carbonyl, phenoxazine and chlorine-substituted carbazole derivatives are synthesized and characterized. They own distinct aggregation-induced delayed fluorescence (AIDF) feature, and exhibit high photoluminescence efficiencies and short delayed fluorescence lifetimes in neat films. The RISC is conspicuously accelerated owing to their tiny singlet-triplet energy splitting and greatly enhanced spin-orbit coupling by heavy atom effect in neat films. They can function efficiently as light-emitting layers in nondoped OLEDs, providing excellent maximum electroluminescence (EL) efficiencies of 20.4–21.7%, and can also perform outstandingly in doped OLEDs in a wide doping concentration range (5–90 wt%), affording impressive EL efficiencies of up to 100.1 cd A–1, 104.8 lm W–1 and 29.1%, with small efficiency roll-off. These findings demonstrate the AIDF luminogens with fast RISC are promising candidates to fulfill various demands of production and application of OLEDs.
关键词： OLEDs,Reverse Intersystem Crossing,Luminogens,Aggregation-Induced Delayed Fluorescence,High-Performance
更新于2025-09-11 14:15:04
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Mechanical Insights into Aggregation-Induced Delayed Fluorescence Materials with Anti-Kasha Behavior
摘要： Organic materials with aggregation-induced delayed fluorescence (AIDF) have exhibited impressive merits for improving electroluminescence efficiency and decreasing efficiency roll-off of nondoped organic light-emitting diodes (OLEDs). However, the lack of comprehensive insights into the underlying mechanism may impede further development and application of AIDF materials. Herein, AIDF materials consisting of benzoyl serving as an electron acceptor, and phenoxazine and fluorene derivatives as electron donors are reported. They display greatly enhanced fluorescence with increased delayed component upon aggregate formation. Experimental and theoretical investigations reveal that this AIDF phenomenon can be rationally ascribed to the suppression of internal conversion and the promotion of intersystem crossing in solid. Moreover, the theoretical calculations disclose that the efficient solid-state delayed fluorescence originates from the higher energy electronic excited state (e.g., S2) rather than the lowest energy-excited state (S1), demonstrating an anti-Kasha behavior. The excellent AIDF property allows high exciton utilization and thus superb performance of OLEDs using these new materials as light-emitting layers.
关键词： aggregation-induced delayed fluorescence,anti-Kasha emission,intersystem crossing,internal conversion,organic light-emitting diodes
更新于2025-09-09 09:28:46