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1.
Nat Commun ; 10(1): 4247, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31534166

RESUMO

Long-lived room temperature phosphorescence (LRTP) is an attractive optical phenomenon in organic electronics and photonics. Despite the rapid advance, it is still a formidable challenge to explore a universal approach to obtain LRTP in amorphous polymers. Based on the traditional polyethylene derivatives, we herein present a facile and concise chemical strategy to achieve ultralong phosphorescence in polymers by ionic bonding cross-linking. Impressively, a record LRTP lifetime of up to 2.1 s in amorphous polymers under ambient conditions is set up. Moreover, multicolor long-lived phosphorescent emission can be procured by tuning the excitation wavelength in single-component polymer materials. These results outline a fundamental principle for the construction of polymer materials with LRTP, endowing traditional polymers with fresh features for potential applications.

2.
Chem Commun (Camb) ; 55(18): 2640-2643, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30742191

RESUMO

Organometallic compounds as photoactive materials are relatively new in organic solar cells. Upon cyclometalation, the octahedral heteroleptic Ir complex TBzIr exhibits significantly enhanced optical-absorption and improved film-morphology compared to the planar organic 2-(5''-hexyl-[2,2':5',2''-terthiophen]-5-yl)benzo[d]thiazole (TBz) ligand. Thus, a dramatically improved power conversion efficiency (PCE) from ∼0 to 3.81% is attained when combined with PC71BM.

3.
Nat Commun ; 9(1): 1754, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29717123

RESUMO

Organocatalytic polymerization reactions have a number of advantages over their metal-catalyzed counterparts, including environmental friendliness, ease of catalyst synthesis and storage, and alternative reaction pathways. Here we introduce an organocatalytic polymerization method called benzylic chloromethyl-coupling polymerization (BCCP). BCCP is catalyzed by organocatalysts not previously employed in polymerization processes (sulfenate anions), which are generated from bench-stable sulfoxide precatalysts. The sulfenate anion promotes an umpolung polycondensation via step-growth propagation cycles involving sulfoxide intermediates. BCCP represents an example of an organocatalyst that links monomers by C=C double bond formation and offers transition metal-free access to a wide variety of polymers that cannot be synthesized by traditional precursor routes.

4.
Adv Mater ; 30(20): e1706246, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29603457

RESUMO

Developing environmentally friendly perovskites has become important in solving the toxicity issue of lead-based perovskite solar cells. Here, the first double perovskite (Cs2 AgBiBr6 ) solar cells using the planar structure are demonstrated. The prepared Cs2 AgBiBr6 films are composed of high-crystal-quality grains with diameters equal to the film thickness, thus minimizing the grain boundary length and the carrier recombination. These high-quality double perovskite films show long electron-hole diffusion lengths greater than 100 nm, enabling the fabrication of planar structure double perovskite solar cells. The resulting solar cells based on planar TiO2 exhibit an average power conversion efficiency over 1%. This work represents an important step forward toward the realization of environmentally friendly solar cells and also has important implications for the applications of double perovskites in other optoelectronic devices.

5.
Adv Sci (Weinh) ; 4(4): 1600166, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28435770

RESUMO

The fluorophores with long-lived fluorescent emission are highly desirable for time-resolved fluorescence imaging (TRFI) in monitoring target fluorescence. By embedding the aggregates of a thermally activated delayed fluorescence (TADF) dye, 2,3,5,6-tetracarbazole-4-cyano-pyridine (CPy), in distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol) (DSPE-PEG2000) matrix, CPy-based organic dots (CPy-Odots) with a long fluorescence lifetime of 9.3 µs (in water at ambient condition) and high brightness (with an absolute fluorescence quantum efficiency of 38.3%) are fabricated. CPy-Odots are employed in time-resolved and confocal fluorescence imaging in living Hela cells and in vivo. The green emission from the CPy-Odots is readily differentiated from the cellular autofluorescence background because of their stronger emission intensities and longer lifetimes. Unlike other widely studied DSPE-PEG2000 encapsulated Odots which are always distributed in cytoplasm, CPy-Odots are located mainly in plasma membrane. In addition, the application of CPy-Odots as a bright microangiography agent for TRFI in zebrafish is also demonstrated. Much broader application of CPy-Odots is also prospected after further surface functionalization. Given its simplicity, high fluorescence intensity, and wide availability of TADF materials, the method can be extended to develop more excellent TADF Odots for accomplishing the challenges in future bioimaging applications.

6.
Adv Mater ; 28(16): 3122-30, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-26923460

RESUMO

A universal thermally activated delayed fluorescence (TADF) host, 4'-diphenylphosphinoylspiro[fluorene-9,9'-xanthene] (SFXSPO), is constructed with a highly distorted and asymmetric configuration and disordered molecular packing in its solid state. SFXSPO successfully endows its full-color TADF diodes with state-of-the-art performance, e.g., the record external quantum efficiency of 22.5% and 19.1% and internal quantum efficiency of ≈100% for its yellow TADF diodes and single-host full-TADF nearly-white-emitting devices, respectively.

7.
Chem Commun (Camb) ; 51(65): 13024-7, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26179717

RESUMO

The non-conjugated inductive effect of trifluoromethyl (CF3) was found to be a new acceptor instead of other conjugated moieties. Two blue emissive compounds, 4CzCF3Ph and 5CzCF3Ph, were synthesized using a simple catalyst-free C-N coupling reaction. Solution-processed TADF devices based on the 5CzCF3Ph dopant exhibit significantly higher efficiency (11.8 cd A(-1), 5.2%) than 4CzCF3Ph (1.03 cd A(-1), 0.67%) due to the smaller ΔE(ST) value for efficient RISC.

8.
Adv Mater ; 27(23): 3546-52, 2015 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-25946623

RESUMO

Various low ratios of triplet iridium complexes (0, 0.5, 1, 1.5, 2.5, and 5 mol%) are conjugated to the backbone of the famous champion donor polymer PTB7. At the same conditions, the power conversion efficiency for polymer containing 1% of Ir increases by 45%, 39%, and 31% in three batches of devices compared with control Ir-free PTB7.

9.
Chem Commun (Camb) ; 51(9): 1650-3, 2015 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-25500635

RESUMO

By using various fluoro-substituted pyridines and carbazole as starting materials, we have synthesized a series of carbazole-pyridine hybrid compounds through an efficient catalyst free C-N coupling reaction with high yields of 85-95%. The bi-, tri- and tetra-carbazole substituted pyridine derivatives exhibit increased thermal stabilities and comparatively high triplet energy levels of ∼3.0 eV. By using them as host materials for blue phosphorescent OLEDs, maximum current efficiencies are achieved ranging from 32-42 cd A(-1).

10.
Chem Soc Rev ; 40(5): 2943-70, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21369622

RESUMO

Phosphorescent organic light-emitting diodes (PhOLEDs) unfurl a bright future for the next generation of flat-panel displays and lighting sources due to their merit of high quantum efficiency compared with fluorescent OLEDs. This critical review focuses on small-molecular organic host materials as triplet guest emitters in PhOLEDs. At first, some typical hole and electron transport materials used in OLEDs are briefly introduced. Then the hole transport-type, electron transport-type, bipolar transport host materials and the pure-hydrocarbon compounds are comprehensively presented. The molecular design concept, molecular structures and physical properties such as triplet energy, HOMO/LUMO energy levels, thermal and morphological stabilities, and the applications of host materials in PhOLEDs are reviewed (152 references).

11.
Phys Chem Chem Phys ; 12(10): 2438-42, 2010 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-20449357

RESUMO

A new host tBu-o-CzOXD is facilely synthesized through a simple aromatic nucleophilic substitution reaction between 3,6-di-tert-butyl-9H-carbazole and 2,5-bis(2-fluorophenyl)-1,3,4-oxadiazole. Its thermal, electrochemical, electronic absorption and photoluminescent properties are fully investigated. A high glass transition temperature (T(g)) of 149 degrees C is observed for tBu-o-CzOXD due to the introduction of bulky tert-butyl moiety, significantly higher than 97 degrees C of o-CzOXD without tert-butyl substituent. Moreover, encapsulation of tert-butyl on the 3- and 6-positions of carbazole greatly enhances the electrochemical stability as compared to o-CzOXD. Green phosphorescent OLEDs hosted by tBu-o-CzOXD show a maximum luminance of 48293 cd m(-2) at 17.1 V, a maximum current efficiency of 38.4 cd A(-1) and a maximum power efficiency of 34.7 lm W(-1). Furthermore, the devices exhibit a slow current efficiency roll-off. The device merits, together with the excellent morphological and electrochemical stability, make the new compound an ideal host material for phosphorescent emitters.


Assuntos
Carbazóis/química , Luminescência , Oxidiazóis/química , Simulação por Computador , Eletroquímica , Medições Luminescentes , Modelos Químicos
12.
Chem Asian J ; 5(2): 278-84, 2010 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-20063341

RESUMO

A series of 9,9'-spirobifluorene/oxadiazole hybrids with various linkages between two components, namely SBF-p-OXD (1), SBF-m-OXD (2), and SBF-o-OXD (3) are designed and synthesized through Suzuki cross-coupling reactions. The incorporation of a rigid and bulky spirobifluorene moiety greatly improves their thermal and morphological stability, with T(d) (decomposition temperature) and T(g) (glass transition temperature) in the ranges of 401-480 degrees C and 136-210 degrees C, respectively. 2 and 3 with meta- and ortho-linkage display higher triplet energy and blue-shifted absorption and emission than their para-linked analogue 1 owing to the decreasing pi-conjugation between the two components. Their HOMO and LUMO energy levels depend on the linkage modes within the range of 5.57-5.64 eV and 2.33-2.49 eV, respectively. Multilayer deep red electrophosphorescent devices with 1-3 as hosts were fabricated and their EL efficiencies follow the order of 3 (o)>2 (m)>1 (p), which correlates with their triplet energy and the separation of HOMO and LUMO distributions at molecular orbitals. The maximum external quantum efficiencies of 11.7% for green and 9.8% for deep red phosphorescent organic light-emitting diodes (OLEDs) are achieved by using 2 and 3 as host materials, respectively.


Assuntos
Fluorenos/química , Oxidiazóis/química , Compostos de Espiro/química , Eletroquímica , Medições Luminescentes , Modelos Químicos , Estrutura Molecular , Espectrometria de Fluorescência
13.
Chem Commun (Camb) ; (23): 3398-400, 2009 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-19503883

RESUMO

Two bridged triphenylamine-triphenylsilane (BTPASi) hybrids have been designed as host materials for phosphorescent OLEDs; devices with the novel host materials achieve maximum external quantum efficiencies as high as 15.4% for blue and 19.7% for green electrophosphorescence.

14.
Org Lett ; 11(12): 2607-10, 2009 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-19459696

RESUMO

4-Bromo-9,9'-spirobifluorene is facilely synthesized, and from this precursor, two ortho-linked oligo-9,9'-spirobifluorenes, 44BSF and 24TSF, are constructed. Devices with 24TSF as the full-hydrocarbon host material and Ir(ppy)(3) or (ppq)(2)Ir(acac) as the triplet emitter show maximum external quantum efficiencies of 12.6 and 10.5% for green and red electrophosphorescence, respectively.

15.
Org Lett ; 11(7): 1503-6, 2009 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-19256517

RESUMO

A fully diarylmethylene-bridged triphenylamine derivative is efficiently synthesized. It has an almost planar triphenylamine (TPA) skeleton and exhibits excellent thermal and morphological stability. Devices with the novel TPA derivative as host material and Ir(ppy)(3) as triplet emitter show a maximum current efficiency of 83.5 cd/A and a maximum power efficiency of 71.4 lm/W for green electrophosphorescence.

16.
Chem Commun (Camb) ; (1): 77-9, 2009 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-19082004

RESUMO

Two simple triphenylamine/oxadiazole derivatives were synthesized and fully characterized; their multifunctionality as highly efficient non-doped blue fluorescence, excellent red phosphorescent host and single-doped two-color based white OLEDs has been demonstrated.

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