Weaving host matrices with intermolecular hydrogen bonds for high-efficiency white thermally activated delayed fluorescence

Tian, Yuee; Wang, Huiqin; Man, Yi; Zhang, Nan; Zhang, Jing; Li, Ying; Han, Chunmiao; Xu, Hui

doi:10.1039/d1sc04188f

Cited by 10 publications

(2 citation statements)

References 59 publications

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“…Furthermore, due to microcavity effect, long-wavelength component in EL spectrum of CzAcSF-hosted device was reduced, resulting in the remarkably narrowed EL profile. [22] The maximum luminance of CzAcSF : 20 % wt. cluster based diodes was beyond 6000 nits, which was 1.6 and 2 folds of host-free and BCPO hosted devices (Figures 1f and S11-S13 and Table 1).…”

Section: Resultsmentioning

confidence: 99%

Cluster Light‐Emitting Diodes Containing Copper Iodine Cube with 100 % Exciton Utilization Using Host‐Cluster Synergy

et al. 2023

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Clusters combine the advantages of organic molecules and inorganic nanomaterials, which are promising alternatives for optoelectronic applications. Nonetheless, recently emerged cluster light‐emitting diodes require further excited state optimization of cluster emitters, especially to reduce population of the cluster‐centered triplet quenching state (3CC). Here we report that redox‐active ligands enhance reverse intersystem crossing (RISC) of Cu4I4 cluster for triplet‐to‐singlet conversion, and thermally activated delayed fluorescence (TADF) host can provide an external RISC channel. It indicates that the complementarity between TADF host and cluster in RISC transitions gives rise to 100 % triplet conversion efficiency and complete singlet exciton convergence, rendering 100‐fold increased singlet radiation rate constant and tenfold decreased triplet non‐radiation rate constant. We achieve a photoluminescence quantum yield of 99 % and a record external quantum efficiency of 29.4 %.

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Section: Resultsmentioning

confidence: 99%

Cluster Light‐Emitting Diodes Containing Copper Iodine Cube with 100 % Exciton Utilization Using Host‐Cluster Synergy

et al. 2023

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“…[7l,14] Therefore, "ideal" hosts in all-TADF WOLEDs should effectively suppress quenching effects, and simultaneously balance carrier flux and exciton allocation. [15] The previous reports showed that regular intermolecular hydrogen bond (IHB) networks in host matrixes can establish effective carrier transportation channels to balance carrier flux, which facilitates carrier recombination, therefore reduces excessive hole or electron induced triplet-polaron quenching (TPQ) (Figure 1A). [16] In opposite, despite weaker electrical properties, random IHBs in host matrixes can lead to disordered molecular alignment in EMLs, therefore alleviating host-dopant and dopant-dopant interaction induced triplet-triplet annihilation (TTA).…”

Section: Introductionmentioning

confidence: 99%

Overcoming power efficiency limitation of white fluorescence light‐emitting diodes via multilevel‐hydrogen‐bond matrix

Man

et al. 2023

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High power efficiency and low efficiency roll‐off at practical luminance are two requirements for new‐generation energy‐saving lighting technologies, which are still bottlenecks of thermally activated delayed fluorescence (TADF) white organic light‐emitting diodes (WOLED), despite the advantages of TADF materials and devices in low cost and high sustainability. Herein, we developed a spiro phosphine oxide host named SSOXSPO, which can form multiple and multidirectional intermolecular hydrogen bonds (IHB). The resulted multilevel IHB network integrates long‐range ordered and short‐range disordered alignments for suppressing triplet‐polaron quenching (TPQ) and triplet‐triplet annihilation (TTA). Electronic characteristics of SSOXSPO matrix are further regulated, leading to the optimal exciton allocation through balancing energy and charge transfer. As consequence, using SSOXSPO as host, the single‐emissive‐layer TADF WOLEDs realized the record performance, including ultralow operation voltage as ∼4.0 V, power efficiency beyond fluorescent tube (70.1 lm W−1) and negligible external quantum efficiency roll‐off (3%) at 1000 nits for indoor lighting. This work demonstrates that multiple interplays supported by host matrixes in TADF WOLEDs can facilitate the synergistic effects of TADF emitters on 100% exciton utilization.

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Asymmetric Ternary Spiro Phosphine Oxide Hosts for Yellow Thermally Activated Delayed Fluorescence Diodes with External Quantum Efficiency Beyond 30%

Wang,

Man,

Zhang

et al. 2023

Advanced Optical Materials

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Yellow thermally activated delayed fluorescence (TADF) organic light‐emitting diodes (OLEDs) are indispensable for lighting, navigation, caution, and so on; however, their development is far behind those of three‐elementary‐color and white analogs, partially because of the lack of host specificity. In this contribution, spiro[bithoxanthene] (ST) and spiro[thioxanthene‐xanthene] (STX) are used as spiro skeletons to form asymmetric ternary structures through introducing two electron‐donating tert‐butyl carbazole (tBCz) and one electron‐withdrawing diphenyl phosphine oxide (DPPO) groups on different rings. The resulting hosts named STSPOtBCz2 and STXSPOtBCz2 not only inherit the steric hindrance of their spiro skeletons, but also achieve the ambipolar characteristics. Their suitable triplet energy levels (T1) of ≈2.5 eV support efficient energy transfer to a conventional yellow TADF emitter 4CzTPNBu with the T1 of ≈2.2 eV. It is shown that compared to STSPOtBCz2 with a symmetric core, the accumulated asymmetry of the spiro skeleton and the kind, number, and position of substitution groups in STXSPOtBCz2 further suppresses the emission quenching, resulting in the state‐of‐the‐art photoluminescent and electroluminescent quantum efficiencies of 93% and 30.6%, respectively. The maximum power efficiency beyond 90 lm W−1 further demonstrates the great potential of multi‐asymmetric host systems for energy‐saving practical application.

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Weaving host matrices with intermolecular hydrogen bonds for high-efficiency white thermally activated delayed fluorescence

Abstract: Thermally activated delayed fluorescence (TADF) white organic light-emitting diode (WOLED) holds great promise for low-cost, large-scale lighting applications. Nevertheless, manipulating exciton allocation in a white TADF single layer is still...

Cited by 10 publications

References 59 publications

Cluster Light‐Emitting Diodes Containing Copper Iodine Cube with 100 % Exciton Utilization Using Host‐Cluster Synergy

Cluster Light‐Emitting Diodes Containing Copper Iodine Cube with 100 % Exciton Utilization Using Host‐Cluster Synergy

Overcoming power efficiency limitation of white fluorescence light‐emitting diodes via multilevel‐hydrogen‐bond matrix

Asymmetric Ternary Spiro Phosphine Oxide Hosts for Yellow Thermally Activated Delayed Fluorescence Diodes with External Quantum Efficiency Beyond 30%

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