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Advances in achieving high external quantum efficiency (EQE) of near‐infrared (NIR) organic light‐emitting diodes (OLEDs) are lagging behind that of the visible‐light OLEDs, according to the energy gap law. Herein, two structurally simple NIR‐phosphorescent Ir(III) complexes, DTCNIr and PTCNIr, with the cyclometalated ligands functionalized by the 1‐phenylisoquinoline‐4‐carbonitrile moiety and thieno/benzo[b]thiophene moiety are handily accessed within three synthetic steps. The introduction of the cyano unit can significantly lower the lowest unoccupied molecular orbitals whereas incorporating the conjugated group can elevate the highest occupied molecular orbitals of the newly designed Ir(III) complexes. The intramolecular charge transfer (ICT) transitions are enhanced due to the increased donor–acceptor interaction inside the metallophosphor. As a result, the emissions are red‐shifted to the NIR region with fast radiative decay. A maximum external quantum efficiency (EQE) of 8.11% with the emission peak at 726 nm for DTCNIr and a maximum EQE of 6.39% with the emission peak at 763 nm for PTCNIr are achieved in the NIR OLEDs by using these Ir(III) materials as the dopant emitters, a champion efficiency in the Ir(III)‐based OLEDs with the emission peak exceeding 760 nm. [ABSTRACT FROM AUTHOR]

A series of heteroleptic Ir(III) complexes composed of two cyclometalated C^N ligands and one dipyrrinato ligand used as an ancillary ligand are synthesized and characterized. With the introduction of a fluorine atom, phenyl ring or diphenylamino group into both C^N ligands and by keeping the ancillary ligand unchanged, these Ir(III) dipyrrinato phosphors do not show an obvious shift in their emission bands. They exhibit emissions extending well into the near-infrared region with an intense band located at around 685 nm in both photo- and electroluminescence spectra, and the deep red to near-infrared organic light emitting diodes (OLEDs) based on them afforded a maximum external quantum efficiency of 2.8%. Density functional theory (DFT) calculations show that both the electronic contributions on the lowest unoccupied molecular orbitals (LUMOs) and the highest energy semi-occupied molecular orbitals (HSOMOs) are mainly localized on the dipyrrinato ligand, indicating that the ancillary ligand, which remains unchanged in this series, exhibits a lower triplet state energy in the iridium phosphors than those involving the C^N ligands. Therefore a switch from "(C^N)2Ir" to dipyrrinato ligand-based emission is observed in these iridium(III) complexes. [ABSTRACT FROM AUTHOR]

Realizing of full-color quantum-dot LED display remains a challenge because of the poor stability of the blue quantum-dot and the immature inkjet-printing color patterning technology. Here, we develop a multifunctional tandem LED by stacking a yellow quantum-dot LED with a blue organic LED using an indium–zinc oxide intermediate connecting electrode. Under parallel connection and alternate-current driving, the tandem LED is full-color-tunable, which can emit red, green and blue primary colors as well as arbitrary colors that cover a 63% National Television System Committee color triangle. Under series connection and direct current driving, the tandem LED can emit efficient white light with a high brightness of 107000 cd m−2 and a maximum external quantum efficiency up to 26.02%. The demonstrated hybrid tandem LED, with multi-functionality of full-color-tunability and white light-emission, could find potential applications in both full-color-display and solid-state-lighting. Designing efficient light-emitting diodes with full-color-tunability and white-light-emission remains a challenge. Here, the authors demonstrate a multifunctional hybrid tandem LED by stacking a yellow quantum-dot LED with a blue organic LED using an indium–zinc oxide intermediate connecting electrode. [ABSTRACT FROM AUTHOR]

The unique features of solution‐processed quantum dots (QDs) including emission tunability in the visible range, high‐quality saturated color and outstanding intrinsic stability in environment are highly desired in various application fields. Especially, for the preparation of wide color gamut displays, QDs with high photoluminescence quantum yield are deemed as the optimal fluorescent emitter that has been utilized in the backlight for liquid crystal display. Nevertheless, the commercialization of electrically driven self‐emissive quantum dot light‐emitting diode (QLED) display is the ultimate target due to its merits of high contrast, slim configuration and compatibility with flexible substrate. Through the great efforts devoted to material engineering and device configuration, astonishing progresses have been made in device performance, giving the QLED technology a great chance to compete with other counterparts for next‐generation displays. In this review, we retrospect the development roadmap of QLED technology and introduce the essential principles in the QLED devices. Moreover, we discuss the key factors that affect the QLED efficiency and lifetime. Finally, the advances in device architectures and pixel patterning are also summarized. [ABSTRACT FROM AUTHOR]

In this work, we report a new blue AIEgen, (9,9-dimethyl-7-(4-(1,2,2-triphenylvinyl)phenyl)-9H-fluoren-2-yl)dimesitylborane (TPE-FB), composed of dimesitylboryl, fluorene and tetraphenylethene (TPE) groups. The thermal stability, electronic structure, optical properties, transient fluorescence decay and electroluminescence of TPE-FB are studied. TPE-FB shows high thermal stability and good aggregation-induced emission (AIE) properties. Due to the presence of the dimesitylboryl group, TPE-FB can interact with fluorine ions to cause a blue-shift in the absorption spectrum and an apparent decrease in the emission spectrum. TPE-FB also exhibits mechanochromic properties, and the fluorescence color of its solid can be reversibly switched between blue and sky-blue by simple grinding and heating (fuming). TPE-FB can function as a light-emitting layer in nondoped sky-blue OLEDs with good performances. [ABSTRACT FROM AUTHOR]

A dark and conductive electrode based on Mo/MoO x /ITO structure with low resistivity of 1.93 × 10 −4 Ω/cm was fabricated by magnetron sputtering. The demonstrated dark electrode exhibits a low reflectance of 2.4–12.9% within the visible spectral range and average luminous reflectance of 3.3%. To improve the conductivity, pure Mo was first sputtered, followed by depositing a dark and conductive MoO x by introducing O 2 flow during Mo sputtering. In order to further reduce the reflectance and set the lowest reflectance at the wavelength of 550 nm, which is most sensitive to human eyes, an ITO phase changing layer was introduced on top of the MoO x . The demonstrated dark and conductive electrode can serve as bottom contact and can potentially replace the circular polarizer for high contrast top-emitting organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

In this study, the hole-electron balance of quantum dot lightemitting diodes (QDLED) was tuned in order to achieve efficiency enhancement. This hole-electron balance optimization was realized by inserting thin barrier layer in the electron transportation layer. Although the current density was slightly sacrificed because of the electron blocking of the barrier layer, the charge balance was improved hence leading to 123% efficiency enhancement. [ABSTRACT FROM AUTHOR]

Two bifunctional red AIE luminogens with efficient solid-state emission and good hole-transporting characteristics are reported. Efficient non-doped OLEDs are fabricated with high external quantum efficiencies of up to 3.9%. Bilayer EL devices using them as both EMLs and HTLs are fabricated with good performances. [ABSTRACT FROM AUTHOR]

Light outcoupling from organic light-emitting diodes (OLEDs) is essential for developing energy-saving displays and efficient lighting sources. Nanocrystallized organic thin films exhibiting scattering features have been considered as effective light extractors for OLEDs. This paper reviews recent advancements in nanocrystallized thin films and their applications in OLEDs. Due to the advantages of easy preparation and OLED compatibility, nanocrystallized organic thin films can integrate with OLEDs as external or internal light extractors easily. Significant light enhancement has been achieved. The fabrication methods and mechanisms of light enhancement are discussed. [ABSTRACT FROM AUTHOR]

Abstract: 4,4′-bis(1,2,2-triphenylvinyl)biphenyl (BTPE) nanowires have been facilely grown by either post-annealing its vacuum-sublimed amorphous film or slowly evaporating its chloroform solution. The morphology and density of the nanowires can be easily tuned by changing the growth conditions. For example, isolated single nanowires were readily obtained by thermally depositing the BTPE on a heated substrate, while bundles of nanotubes can be achieved by slowly evaporating a droplet of the BTPE solution. The self-assembled BTPE nanowires show enhanced and blue-shifted photoluminescence compared with that of its amorphous film. The nanowires exhibit a highly hydrophobic surface with a water contact angle of 126°. Also, the BTPE nanowires scatter the light effectively due to the random orientation of the wires. By depositing the BTPE nanowires on the backside of the glass substrate as a scattering media for organic light-emitting diodes, a 31.5% efficiency improvement has been achieved. [Copyright &y& Elsevier]

We propose a novel color filter pixel arrangement for improving the color gamut of AMOLED microdisplay. By placing adjacent sub-pixels with same color together, the color cross-talking can be suppressed significantly. For example, in a RGBW format, simulation shows that a ∼50% reduction of color cross-talking, and thus a 41% improvement of color gamut can be achieved by employing the proposed color filter pixel arrangement. [ABSTRACT FROM AUTHOR]

Enlarged tetrasubstituted alkenes with high fluorescent efficiency and good thermal stability are constructed. They exhibit luminance up to 35 160 cd m−2 and efficiency of 16 cd A−1 in OLEDs. [ABSTRACT FROM AUTHOR]

A phenanthroline‐based donor–acceptor type fluorophore is designed and synthesized, and its thermal, photophysical, and electrochemical characteristics are investigated. This fluorophore displays a strong deep‐red/near‐infrared (DR/NIR) emission with the photoluminescence quantum yield of 74.8% in nonpolar n‐hexane solvent and 4.5% in polar chloroform solvent, as well as 1.26% in neat film and 18.4% in 5 wt% doped poly(methyl methacrylate) film. DR/NIR devices are fabricated, with emission peaks at 670–696 nm and external quantum efficiencies of 3.18–1.43% at different doping concentrations. Deep‐red/near‐infrared organic light‐emitting diodes with emission peaks at 670–696 nm and external quantum efficiencies of 3.18–1.43% are fabricated using a novel donor–acceptor‐type and wedge‐shaped organic fluorophore 2TPA‐PPDC. [ABSTRACT FROM AUTHOR]

A transparent and conductive electrode based on hydrogen (H) doped ZnO has been proposed for active-matrix (AM) display applications. With optimal H plasma power and treat time, the resultant ZnO:H exhibits a low sheet resistance of 200 ohm/sq at a thickness of 150 nm. The demonstrated transparent and conductive ZnO:H can serve as electrode for LCD or OLED as well as S/D electrode for ZnO TFT. With proposed ZnO:H electrode, two photomask steps can be reduced in the fabrication of ZnO TFT-based AM backplanes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Side-by-side color tunable OLEDs have been fabricated without fine mask alignment. [•] The color tunable OLEDs consist of orange inverted sub-OLEDs and blue sub-OLEDs; both shares the same electrodes. [•] With AC driving, the orange inverted sub-OLEDs and blue sub-OLEDs are alternately turn on. [•] The color can be continuously tuned by varying the amplitude ratio of the positive and the negative pulses. [ABSTRACT FROM AUTHOR]

Emissive electron donor–acceptor (D–A)conjugateshave a wide variety of applications in biophotonics, two-photon absorptionmaterials, organic lasers, long wavelength emitters, and so forth.However, it is still a challenge to synthesize high solid-state efficiencyD–A structured emitters due to the notorious aggregation-causedquenching (ACQ) effect. Though some D–A systems are reportedto show aggregation-induced emission (AIE) behaviors, most are onlyselectively AIE-active in highly polar solvents, showing decreasedsolid-sate emission efficiencies compared to those in nonpolar solvents.Here we report the triphenylamine (TPA) and 2,3,3-triphenylacrylonitrile(TPAN) based D–A architectures, namely, TPA3TPAN and DTPA4TPAN.Decoration of arylamines with TPAN changes their emission behaviorsfrom ACQ to AIE, making resulting TPA3TPAN and DTPA4TPAN nonluminescentin common solvents but highly emissive when aggregated as nanoparticles,solid powders, and thin films owing to their highly twisted configurations.Both compounds also display a bathochromic effect due to their intramolecularcharge transfer (ICT) attribute. Combined ICT and AIE features renderTPA3TPAN and DTPA4TPAN intense solid yellow emitters with quantumefficiencies of 33.2% and 38.2%, respectively. They are also thermallyand morphologically stable, with decomposition and glass transitiontemperatures (Td/Tg) being 365/127 and 377/141 °C, respectively. Multilayerelectroluminescence (EL) devices are constructed, which emit yellowEL with maximum luminance, current, power, and external quantum efficienciesup to 3101 cd/m2, 6.16 cd/A, 2.64 lm/W, and 2.18%, respectively.These results indicate that it is promising to fabricate high efficiencyAIE-ICT luminogens with tunable emissions through rational combinationand modulation of propeller-like donors and/or acceptors, thus pavingthe way for their biophotonic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of two aggregation-induced emission materials ( PPBC and DPPBC ) with different conjugate strengths of penylethene-carbazole moieties. Their structures have been characterized by nuclear magnetic resonance spectroscopy, high-resolution mass spectra and elemental analysis. Besides, their thermal, photophysical, electrochemical and electroluminescent properties are investigated systematically. Their electrical structures are also studied by theoretical methods. The results reveal that they possess good thermal property of decomposition temperature (313 and 214 °C) and low LUMO energy of −1.91 and −1.87 eV. PPBC and DPPBC also show good electrochemical stabilities and optical properties. Non-doped OLED (device I) adopting PPBC as a deep blue emitter presents deep blue emission (the peak is at 441 nm) with CIE coordinates (0.21, 0.22), possessing a turn-on voltage of 4.8 V, a maximum luminance of 7500 cd m −2 , a maximum luminance efficiency of 1.286 cd A −1 and a maximum power efficiency of 1.339 lm/w; and non-doped OLED (device II) fabricated by DPPBC emits blue-green light (the peak is at 508 nm) with CIE coordinates (0.23, 0.45), achieving a turn-on voltage of 3.6 V, a maximum luminance of 10290 cd m −2 , a maximum luminance efficiency of 4.075 cd A −1 and a maximum power efficiency of 2.559 lm/w. The results demonstrate that these new AIE compounds are promising solid-state luminescent materials with practical utility in non-doped OLED. [ABSTRACT FROM AUTHOR]

[Display omitted] • Changing the substituent of cyclometalated ligands of Ir(III) complexes can tune the emission from deep red to NIR. • The evaporation-processed OLEDs furnish the maximum EQEs of 12.68% and 12.49% with the emission peaks at 673 and 692, respectively. • The solution-processed NIR OLEDs furnish the maximum EQE of 3.80 % with the emission peak at 706 nm. Solution processing of organic light-emitting devices (OLEDs) becomes an attractive approach due to its low fabrication cost and accessibility to a broad range of materials. Near-infrared (NIR) OLEDs emerge as a practicable technological medium that can be widely used in phototherapy, optical imaging, remote communication, secured display and so on. We report here a couple of high-performance deep red OLEDs fabricated by evaporation processing and a series of NIR OLEDs fabricated by solution processing, in which the devices attain high maximum external quantum efficiencies (EQEs) of 12.68 %, 12.49 % and 3.80 % with the electroluminescence peaks at 673, 692 and 706 nm, respectively. The effects of functional substituents and p–π conjugation on the optoelectronic properties of these new Ir(III) phosphors have also been investigated. It can provide a new insight into developing highly efficient evaporation-processed and solution-processed OLEDs based on Ir(III) complexes with deep red and NIR emissions. [ABSTRACT FROM AUTHOR]

A scattering film is obtained by thermally evaporating tetraphenylethene (TPE) onto the substrate. The TPE molecules self-crystallize themselves as microsheet on reaching the substrate. The resultant TPE films exhibit strong light scattering effect because of the random distribution of the crystallized sheets. The scattering films, being able to be deposited by thermal evaporation, can thus integrate with top-emitting organic light-emitting diodes (OLEDs) directly. As a result, the top-emitting OLEDs exhibit reduced angular dependence of emission spectra; for example, the color coordinates is only slightly shifted from (0.2891, 0.6001) to (0.2735, 0.5617) when the viewing angle increases from 0° to 80°. [ABSTRACT FROM AUTHOR]

Three new donor-acceptor (D-A) chromophores decorated with bis(trifluoromethyl)-substituted phenyl group as acceptor and bis(4-(9 H -carbazol-9-yl)phenyl)amine as donor unit, namely 1,4-naphthyl-CF 3 (1), 1,5-naphthyl-CF 3 (2) and Ph-CF 3 (3), were designed and synthesized. Their photophysical and electrochemical characteristics, and corresponding theoretical calculations were investigated. They showed blue emissions with high photoluminescence quantum yields (PLQY). Doped organic light-emitting diodes (OLEDs) based on them were fabricated, which exhibited strong blue electroluminescence with emission peaks at 453, 446 and 440 nm and full width at half maximum (FWHM) of 69, 65 and 65 nm, respectively. Their Commission International del'Eclairage (CIE) coordinates correspond to (0.169, 0.158), (0.176, 0.134) and (0.163, 0.099). Besides, the maximum current efficiencies (CEs) of 2.8, 5.0 and 4.9 cd A−1; power efficiencies (PEs) of 2.9, 5.4 and 5.2 lm W−1; external quantum efficiencies (EQEs) of 2.3, 2.3 and 3.4% were achieved for 1,4-naphthyl-CF 3 (1), 1,5-naphthyl-CF 3 (2) and Ph-CF 3 (3) doped devices D1, D2 and D3, respectively. This study clearly showed that the optoelectronic properties of these organic small molecules can be regulated by rational design of molecular structures, and their emission wavelengths could be finely tuned within the blue region. [Display omitted] • Three new CF 3 -substituted blue emitters with donor-acceptor structure are first designed and synthesized. • Pure deep blue emission with CIE coordinate of (0.163, 0.099) is found. • Narrow emission with FWHM of 69, 65 and 65 nm is achieved. • Fine tuning of the electroluminescence wavelength within the blue region is realized. [ABSTRACT FROM AUTHOR]