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The First Egongyan Bridge in Chongqing, China was opened to traffic on December 27, 2000. It carries six-lanes of city traffic and two pedestrian paths, one on each side. It is a 600 m span suspension bridge. It was planned that the two pedestrian paths might eventually be converted to transit tracks in the future. However, with the rapid increase in urban traffic, the deck was transformed into an 8-lane bridge instead. Therefore, a new bridge parallel and adjacent to the old bridge was built for the rail transit. For aesthetic reasons, the city decided that the new bridge should also be a suspension bridge, with the same span length and tower height as the first bridge. The First Egongyan Bridge was a true suspension bridge with main cables anchored to ground anchors. However, the new bridge bridge's proximity to the first bridge necessitated the construction of a self-anchored suspension bridge that did away with a second set of ground anchors. This 600 m span happened to be the world's longest span for a self-anchored suspension bridge. [ABSTRACT FROM AUTHOR]

The advancement of high-efficiency luminescent and thermally stable organometallic complexes has offered opportunities for the commercialization of metal phosphors for fabricating organic light-emitting devices (OLEDs). Since the first report on the potential use of iridium-(III) and platinum-(II) complexes for applications in OLEDs in the late 1990s, extensive efforts have been made by researchers on the development of various heavy metal-containing compounds with rich photophysical and luminescence properties and the engineering of device architectures to improve device efficiencies. Apart from the more well-studied iridium-(III) and platinum-(II) complexes, complexes of gold-(III) recently have demonstrated their capabilities to serve as phosphorescent or thermally stimulated delayed phosphorescent or thermally activated delayed fluorescent emitters, and their promising performances in OLEDs have attracted growing interest in the past decade. Nowadays, complexes of gold-(III) with emission energies ranging from sky-blue to near-infrared with high electroluminescence performances have been obtained. In addition, high-efficiency vacuum-deposited and solution-processed OLEDs with benchmark efficiencies comparable to those of the iridium-(III) and platinum-(II) complexes have been realized. This Focus Review summarizes the development of various series of luminescent gold-(III) complexes to date and highlights important milestones in the development and advancement of gold-(III)-based OLEDs. Focus will be made on the molecular design strategies for gold-(III) emitters for application as dopants in OLEDs, including those fabricated by vacuum-deposition and solution-processing techniques. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a novel one‐pot synthetic method towards a series of boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs, 1 a–1 o), including hitherto unknown B‐doped zethrene derivatives, from ortho‐aryl substituted diarylalkynes with high atom efficiency and broad substrate scopes. A reaction mechanism is proposed based on the experimental investigation together with the theoretical calculations, which involves a unique 1,4‐boron migration process. The resultant benchtop‐stable B‐PAHs are thoroughly investigated by X‐ray crystallography, cyclic voltammetry, UV/Vis absorption, and fluorescence spectroscopies. The blue and green organic light‐emitting diode (OLED) devices based on 1 f and 1 k are further fabricated, demonstrating the promising application potential of B‐PAHs in organic optoelectronics. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a novel one‐pot synthetic method towards a series of boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs, 1 a–1 o), including hitherto unknown B‐doped zethrene derivatives, from ortho‐aryl substituted diarylalkynes with high atom efficiency and broad substrate scopes. A reaction mechanism is proposed based on the experimental investigation together with the theoretical calculations, which involves a unique 1,4‐boron migration process. The resultant benchtop‐stable B‐PAHs are thoroughly investigated by X‐ray crystallography, cyclic voltammetry, UV/Vis absorption, and fluorescence spectroscopies. The blue and green organic light‐emitting diode (OLED) devices based on 1 f and 1 k are further fabricated, demonstrating the promising application potential of B‐PAHs in organic optoelectronics. [ABSTRACT FROM AUTHOR]

Phosphorescent dopants are promising candidates for organic light‐emitting diodes (OLEDs). Although it has been established that the out‐coupling efficiency and overall performances of vacuum‐deposited OLEDs can be significantly improved by a horizontal orientation of the dopants, no horizontally oriented gold(III) complexes have been reported to date. Herein, a novel class of tetradentate C^C^N^N ligand‐containing gold(III) complexes with a preferential horizontal orientation successfully generated through a one‐pot reaction is reported. These complexes demonstrate high photoluminescence quantum yields of 70 % and a high horizontal dipole ratio of 0.87 in solid‐state thin films. Green‐emitting OLEDs based on these complexes operate with a maximum external quantum efficiency of 20.6 % with an estimated out‐coupling efficiency of around 30 %. A promising device stability has been achieved in the vacuum‐deposited OLEDs, with operational half‐lifetimes of around 37 500 h at 100 cd m−2. [ABSTRACT FROM AUTHOR]

Phosphorescent dopants are promising candidates for organic light‐emitting diodes (OLEDs). Although it has been established that the out‐coupling efficiency and overall performances of vacuum‐deposited OLEDs can be significantly improved by a horizontal orientation of the dopants, no horizontally oriented gold(III) complexes have been reported to date. Herein, a novel class of tetradentate C^C^N^N ligand‐containing gold(III) complexes with a preferential horizontal orientation successfully generated through a one‐pot reaction is reported. These complexes demonstrate high photoluminescence quantum yields of 70 % and a high horizontal dipole ratio of 0.87 in solid‐state thin films. Green‐emitting OLEDs based on these complexes operate with a maximum external quantum efficiency of 20.6 % with an estimated out‐coupling efficiency of around 30 %. A promising device stability has been achieved in the vacuum‐deposited OLEDs, with operational half‐lifetimes of around 37 500 h at 100 cd m−2. [ABSTRACT FROM AUTHOR]

Phosphorescent dopants are promising candidates for organic light‐emitting diodes (OLEDs). Although it has been established that the out‐coupling efficiency and overall performances of vacuum‐deposited OLEDs can be significantly improved by a horizontal orientation of the dopants, no horizontally oriented gold(III) complexes have been reported to date. Herein, a novel class of tetradentate C^C^N^N ligand‐containing gold(III) complexes with a preferential horizontal orientation successfully generated through a one‐pot reaction is reported. These complexes demonstrate high photoluminescence quantum yields of 70 % and a high horizontal dipole ratio of 0.87 in solid‐state thin films. Green‐emitting OLEDs based on these complexes operate with a maximum external quantum efficiency of 20.6 % with an estimated out‐coupling efficiency of around 30 %. A promising device stability has been achieved in the vacuum‐deposited OLEDs, with operational half‐lifetimes of around 37 500 h at 100 cd m−2. [ABSTRACT FROM AUTHOR]

A new class of sky‐blue‐ to green‐emitting carbazolylgold(III) C^C^N complexes containing pyrazole or benzimidazole moieties has been successfully designed and synthesized. Through the judicious choice of the N‐heterocycles in the cyclometalating ligand and the tailor‐made carbazole moieties, maximum photoluminescence quantum yields of 0.52 and 0.39 have been realized in the green‐ and sky‐blue‐emitting complexes, respectively. Solution‐processed and vacuum‐deposited organic light‐emitting devices (OLEDs) based on the benzimidazole‐containing complexes have been prepared. The sky‐blue‐emitting device shows an emission peaking at 484 nm with a narrow full‐width at half‐maximum of 57 nm (2244 cm−1), demonstrating the potential of this class of complexes in the application of OLEDs with high color purity. In addition, high maximum external quantum efficiencies of 12.3 % and a long operational half‐lifetime of over 5300 h at 100 cd m−2 have been achieved in the vacuum‐deposited green‐emitting devices. [ABSTRACT FROM AUTHOR]

A new class of sky‐blue‐ to green‐emitting carbazolylgold(III) C^C^N complexes containing pyrazole or benzimidazole moieties has been successfully designed and synthesized. Through the judicious choice of the N‐heterocycles in the cyclometalating ligand and the tailor‐made carbazole moieties, maximum photoluminescence quantum yields of 0.52 and 0.39 have been realized in the green‐ and sky‐blue‐emitting complexes, respectively. Solution‐processed and vacuum‐deposited organic light‐emitting devices (OLEDs) based on the benzimidazole‐containing complexes have been prepared. The sky‐blue‐emitting device shows an emission peaking at 484 nm with a narrow full‐width at half‐maximum of 57 nm (2244 cm−1), demonstrating the potential of this class of complexes in the application of OLEDs with high color purity. In addition, high maximum external quantum efficiencies of 12.3 % and a long operational half‐lifetime of over 5300 h at 100 cd m−2 have been achieved in the vacuum‐deposited green‐emitting devices. [ABSTRACT FROM AUTHOR]

Bipolar cyclometalated dendritic alkynylgold(III) complexes that exhibit excellent film morphologies in solid-state thin films have been designed and synthesized. Together with their high luminescence quantum yields, high performance solution-processable organic light-emitting devices have been realized, maintaining high external quantum efficiencies of >12% for dendrimers up to the second generation. [ABSTRACT FROM AUTHOR]

Abstract: A new class of fused heterocyclic tridentate ligand‐containing alkynylgold(III) complexes with tunable emission color has been successfully designed and synthesized. Structural modification of the σ‐donating fused heterocyclic alkynyl ligands, including substituted fluorene, carbazole, and triphenylamine, enables a large spectral shift of about 110 nm (ca. 3310 cm−1) that covers the green to red region to be realized with the same tridentate ligand‐containing alkynylgold(III) complexes in solid‐state thin films. Interestingly, the energy of the excimeric emission can be controlled by the rational design of the fused heterocyclic alkynyl ligands. Superior solution‐processable organic light‐emitting devices (OLEDs) with high external quantum efficiencies (EQEs) of 12.2, 13.5, 9.3, and 5.2 % were obtained with green, yellow, orange, and red emission. These high EQE values are comparable to those of the vacuum‐deposited OLEDs based on structurally related alkynylgold(III) complexes. [ABSTRACT FROM AUTHOR]

Abstract: A new class of fused heterocyclic tridentate ligand‐containing alkynylgold(III) complexes with tunable emission color has been successfully designed and synthesized. Structural modification of the σ‐donating fused heterocyclic alkynyl ligands, including substituted fluorene, carbazole, and triphenylamine, enables a large spectral shift of about 110 nm (ca. 3310 cm−1) that covers the green to red region to be realized with the same tridentate ligand‐containing alkynylgold(III) complexes in solid‐state thin films. Interestingly, the energy of the excimeric emission can be controlled by the rational design of the fused heterocyclic alkynyl ligands. Superior solution‐processable organic light‐emitting devices (OLEDs) with high external quantum efficiencies (EQEs) of 12.2, 13.5, 9.3, and 5.2 % were obtained with green, yellow, orange, and red emission. These high EQE values are comparable to those of the vacuum‐deposited OLEDs based on structurally related alkynylgold(III) complexes. [ABSTRACT FROM AUTHOR]

A new class of brightly blue-green-emitting arylgold(III) complexes has been synthesized, characterized, and applied as phosphorescent dopants in the fabrication of solution-processable and vacuum-deposited organic light-emitting devices (OLEDs). These arylgold(III) complexes can be readily synthesized by reacting the corresponding arylboronic acids with the gold(III) precursor complexes in a one-pot Suzuki-Miyaura coupling reaction. When compared to the structurally related alkynylgold(III) complex, arylgold(III) complexes 1 and 2 exhibit much higher photoluminescence quantum yields in solution state. High photoluminescence quantum yields are also observed in solid-state thin films. More importantly, the solid-state emission spectra show strong resemblance to those in solution, irrespective of the dopant concentration, leading to significant improvement in the color purity of the OLEDs by suppressing any excimer emission resulting from the π-stacking of the tridentate ligand. High performance solution-processable and vacuum-deposited blue-green-emitting OLEDs have also been realized, with maximum external quantum efficiencies of 7.3% and 14.7%, respectively, representing the first demonstration of efficient blue-green-emitting OLEDs based on cyclometalated arylgold(III) complexes. [ABSTRACT FROM AUTHOR]

Bridges can be categorised by span lengths, such as short-span, medium-span, long-span and super-long-span and also by type, such as girder bridges, arch bridges, cable-stayed bridges and suspension bridges. This paper studies how long a span for each of these four types of bridges can be. [ABSTRACT FROM AUTHOR]

The design process of a bridge can be divided into four basic stages: conceptual design, preliminary design, detailed design and construction design. The purpose of the conceptual design is to come up with various feasible bridge schemes and to decide on one or more final concepts for further consideration. The purpose of the preliminary design is to select the best scheme from these proposed concepts and then to ascertain the feasibility of the selected concept and finally to refine its cost estimates. The purpose of the detailed design is to finalise all the details of the bridge structure so that the document is sufficient for tendering and construction. Finally, the purpose of the construction design is to provide step-by-step procedures for the building of the bridge. [ABSTRACT FROM PUBLISHER]

People have been building beautiful arch bridges for more than 2000 years. From the spectacularly solid Roman arch to today's elegant and graceful styles, there are a large variety of arch shapes. The development of arches was influenced by the construction materials available at the time. Today, with more versatile materials such as steel and reinforced concrete, many beautiful signature arch bridges are being built. [ABSTRACT FROM PUBLISHER]

A novel isoquinoline-containing C^N^C ligand and its phosphorescent triphenylamine-based alkynylgold(III) dendrimers have been synthesized. These alkynylgold(III) dendrimers serve as phosphorescent dopants in the fabrication of efficient solution-processable organic light-emitting devices (OLEDs). The photophysical, electrochemical, and electroluminescence properties were studied. A saturated red emission with CIE coordinates of (0.64, 0.36) and a high EQE value of 3.62 % were achieved. Unlike other red-light-emitting iridium(III) dendrimers, a low turn-on voltage of less than 3 V and a reduced efficiency roll-off at high current densities were observed; this can be accounted for by the enhanced carrier transporting ability and the relatively short lifetimes in the high-generation dendrimers. This class of alkynylgold(III) dendrimers are promising candidates as phosphorescent dopants in the fabrication of solution-processable OLEDs. [ABSTRACT FROM AUTHOR]

The full life cycle costs of a bridge include initial costs, maintenance costs, rehabilitation costs, disposal costs and the oftentimes overlooked cost to society. In most cases, the latter – cost to the society – is typically not considered by estimators. Establishing the cost of a bridge is only half of the equation. The resulting amount alone cannot compare with what the bridge provides to society, that is its value. The value of a bridge encompasses a range of qualities including its functional value, societal value, symbolic value and aesthetic value. The economic feasibility of a bridge project depends on the balance between its cost and its value. The decision to build or not to build a bridge must be based on whether the cost to build it is more or less than the value the bridge holds for people. If the cost is higher, the bridge should not be built. If the value is higher, building the bridge is reasonable. [ABSTRACT FROM AUTHOR]

Emission control: Carbazole‐based dendritic alkynylgold(III) complexes have been evaluated as phosphorescent emitters in organic light‐emitting devices. The energy as well as the bathochromic shift of the emissions can be tuned effectively through a control of the dendrimer generation (see spectra). The optimized devices show high current and external quantum efficiencies of up to 24.0 cd A−1 and 7.8 %, respectively. [ABSTRACT FROM AUTHOR]

Emissionskontrolle: Carbazolbasierte dendritische Alkinylgold(III) ‐ Komplexe wurden als phosphoreszierende Emitter in organischen Leuchtdioden getestet. Die Energie und bathochrome Verschiebung der Emissionen kann effektiv über die Dendrimergeneration eingestellt werden (siehe Spektren). Die optimierten Bauteile weisen hohe Strom ‐ und externe Quanteneffizienzen bis 24.0 cd A−1 bzw. 7.8 % auf. [ABSTRACT FROM AUTHOR]

Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters have been studied to address the issue of the broadband emission in organic light‐emitting diodes (OLEDs). Herein, the authors have systematically investigated the effect of electron‐donating or ‐withdrawing units in the para position of B atom on the optoelectronic emission modulation BCz‐BN MR‐TADF emitters. Due to the enhanced spin‐orbit coupling (SOC) effect, BN(p)SCH3 with electron structure of para‐D‐π‐B is synthesized by introducing a heavy S atom into the para position of B atom of BCz‐BN. By oxidizing BN(p)SCH3, BN(p)SOCH3 and BN(p)SO2CH3 with electron structure of para‐A‐π‐B have been synthesized. The quantum simulations and photophysical studies have illustrated BN(p)SCH3 can exhibit large reverse intersystem crossing rate constant (kRISC) of 6.4 × 104 s−1 due to the large SOC constants and small singlet‐triplet energy splitting (ΔEST) of 0.12 eV. BN(p)SOCH3 and BN(p)SO2CH3 with electron structure of para‐A‐π‐B displayed red‐shift emissions with smaller full‐width at half‐maximum (FWHM) values of ≈21 nm and kRISC values owing to enhanced ΔEST and the low emission contribution of the triplet excitons in contrast to those of BN(p)SCH3 with electron structure of para‐D‐π‐B. Consequently, BN(p)SCH3‐based OLEDs show highly efficient blue emission with an external quantum efficiency (EQE) of 26.2% and excellent color purity. [ABSTRACT FROM AUTHOR]

The 2D MoS2 with superior optoelectronic properties such as high charge mobility and broadband photoresponse has attracted broad research interests in photodetectors (PD). However, due to the atomic thin layer of 2D MoS2, its pure photodetectors usually suffer from inevitable drawbacks such as large dark current, and intrinsically slow response time. Herein, a new organic material BTP‐4F with high mobility is successfully stacked with 2D MoS2 film to form an integrated 2D MoS2/organic P–N heterojunction, facilitating efficient charge transfer as well as significantly suppressed dark current. As a result, the as‐obtained 2D MoS2/organic (PD) has exhibited excellent response and fast response time of 332/274 µs. The analysis validated photogenerated electron transition from this monolayer MoS2 to subsequent BTP‐4F film, whereas the transited electron is originated from the A− exciton of 2D MoS2 by temperature‐dependent photoluminescent analysis. The ultrafast charge transfer time of ≈0.24 ps measured by time‐resolved transient absorption spectrum is beneficial for efficient electron–hole pair separation, greatly contributing to the obtained fast photoresponse time of 332/274 µs. This work can open a promising window to acquire low‐cost and high‐speed (PD). [ABSTRACT FROM AUTHOR]

Herein, a family of six [3+2+1] coordinated 2‐(2′,4′‐difluorophenyl) pyridine‐based Iridium(III) complexes with intermolecular interactions have been designed to improve their emission properties. These molecular interactions have been regarded as an effective way to suppress non‐radiative decay and enhance the photoluminescence quantum yield (PLQY) of the light‐emitting materials. Specifically, complex 3 functionalized with new −CF3 ligand exhibits PLQY of up to 100%, and the emission peak at ≈485 nm with short excited‐state lifetime down to 1 µs. Therefore, the blue phosphorescent organic light‐emitting diode (OLED) based on complex 3 dopant exhibits excellent performance with a maximum external quantum efficiency of 22.0% and low efficiency roll‐off. Upon increasing the current density to 250 mA cm−2, high brightness value of 53 400 cd m−2 is achieved, which is not attainable with the similar molecular structure that we have reported recently, indicating the importance of the presence of the (CF···H/CN···H) interactions. Given the well‐overlapping of the emission spectra of these Iridium(III) complexes and absorption spectrum of v‐DABNA emitter, complex 3 has been successfully applied as a sensitizer for v‐DABNA‐based OLED, and a maximum current efficiency of 27.13 cd A−1 with high brightness level of up to 10 000 cd m−2 have been achieved. [ABSTRACT FROM AUTHOR]

Constructing stable surface modification layer is an effective strategy to suppress dendrite growth and side reactions of Zinc (Zn) metal anode in aqueous Zn‐ion battery. Herein, a multicomponent Cu−Zn alloy interlayer with superior Zn affinity, high toughness and effective inhibition effect on lattice distortion is constructed on Zn foil (Cu−Zn@Zn) to fabricate ultra‐stable Zn metal anode. Owning to the advantages of high binding energy of Cu−Zn alloy layer with Zn atoms and less contact area between metallic Zn and electrolyte, the as‐prepared Cu−Zn@Zn electrode not only restricts the aggregation of Zn atoms, but also suppresses the pernicious hydrogen evolution and corrosion, leading to homogeneous Zn deposition and outstanding electrochemical performances. Accordingly, the symmetric battery with Cu−Zn@Zn electrode exhibits an ultra‐long cycle life of 5496 h at 1 mA cm−2 for 1 mAh cm−2, and the Cu−Zn@Zn//V2O5 pouch cell demonstrates excellent cycling stability with a capacity retention of 88 % after 600 cycles. [ABSTRACT FROM AUTHOR]

Constructing stable surface modification layer is an effective strategy to suppress dendrite growth and side reactions of Zinc (Zn) metal anode in aqueous Zn‐ion battery. Herein, a multicomponent Cu−Zn alloy interlayer with superior Zn affinity, high toughness and effective inhibition effect on lattice distortion is constructed on Zn foil (Cu−Zn@Zn) to fabricate ultra‐stable Zn metal anode. Owning to the advantages of high binding energy of Cu−Zn alloy layer with Zn atoms and less contact area between metallic Zn and electrolyte, the as‐prepared Cu−Zn@Zn electrode not only restricts the aggregation of Zn atoms, but also suppresses the pernicious hydrogen evolution and corrosion, leading to homogeneous Zn deposition and outstanding electrochemical performances. Accordingly, the symmetric battery with Cu−Zn@Zn electrode exhibits an ultra‐long cycle life of 5496 h at 1 mA cm−2 for 1 mAh cm−2, and the Cu−Zn@Zn//V2O5 pouch cell demonstrates excellent cycling stability with a capacity retention of 88 % after 600 cycles. [ABSTRACT FROM AUTHOR]

The PD, comprising a perovskite layer to absorb visible light (500–810 nm) and an organic bulk heterojunction layer for NIR light absorption (810–950 nm), exhibited a voltage-modulated photoresponse range in visible (forward bias) and NIR spectra (reverse bias). A high detectivity, fast microsecond response time and a wide dynamic range (>120 dB) were achieved to enable switchable visible light and NIR imaging. [Display omitted] Visible and near-infrared (NIR) light dual-band photodetectors (PDs) have potential applications in signal detection, bioimaging, optical communications and safety monitoring. Herein, we report an ultrafast perovskite/organic heterojunction dual-mode PD with a voltage-modulated photoresponse range in visible and NIR spectra. The PD, comprising a perovskite layer to absorb visible light (500–810 nm) and an organic bulk heterojunction layer for NIR light absorption (810–950 nm), exhibited a switchable spectral response in the visible or NIR bands. The voltage-modulated visible and NIR photoresponses of the PD were attributable to controlled charge photogeneration in perovskite and organic blend thin films under different bias polarities. The device exhibited peak responsivities of 93.5 and 102.2 mA/W in the visible and NIR bands, respectively; a high detectivity of 4.3 × 109 Jones (at forward bias of 0.7 V and incident 625 nm light) and 1.6 × 1012 Jones (at reverse bias of –1.5 V and incident 900 nm light); a fast microsecond response time; and a wide dynamic range (>120 dB) both in the visible mode and NIR mode. Also, this voltage-modulated dual-band PD shows promising applications in visible light and NIR imaging, which is proven by demonstrating a PD array with 25 pixels (5 × 5). [ABSTRACT FROM AUTHOR]

A correction to the article "Dendritic Luminescent Gold( III) Complexes for Highly Efficient Solution-Processable Organic Light-Emitting Devices" that was published in the 2013 issue is presented.

Solution processable quasi‐2D (Q‐2D) perovskite materials are emerging as a promising candidate for blue light source in full‐color display applications due to their good color saturation property, high brightness, and spectral tunability. Herein, an efficient energy cascade channel is developed by introducing sodium bromide (NaBr) in phenyl‐butylammonium (PBA)‐containing mixed‐halide Q‐2D perovskites for a blue perovskite light‐emitting diode (PeLED). The incorporation of alkali metal contributes to the nucleation and growth of Q‐2D perovskites into graded distribution of domains with different layer number . The study of excitation dynamics by transient absorption (TA) spectroscopy confirms that NaBr induces more Q‐2D perovskite phases with small n number, providing a graded energy cascade pathway to facilitate more efficient energy transfer processes. In addition, the nonradiative recombination within the Q‐2D perovskites is significantly suppressed upon Na+ incorporation, as validated by the trap density estimation. Consequently, the optimized blue PeLEDs manifest a peak external quantum efficiency (EQE) of 7.0% emitting at 486 nm with a maximum luminance of 1699 cd m−2. It is anticipated that these findings will improve the understanding of alkali‐metal‐assisted optimization of Q‐2D perovskites and pave the way toward high‐performance blue PeLEDs. [ABSTRACT FROM AUTHOR]

A new series of blue phosphorescent cyclometalated [3+2+1] coordinated iridium (III) complexes containing 2‐(2′,4′‐difluoropyridyl) pyridine derivatives have been designed and synthesized to investigate their structure–property relationship on the nature of excited states and tune their emission wavelengths from saturated‐blue to sky‐blue region at 437−489 nm. These complexes exhibit high photoluminescent quantum yields (PLQYs) of up to 90% and short excited state lifetime in the range of 2−5 µs in polymethylmethacrylate (PMMA) thin films. Sky‐blue organic light‐emitting diodes (OLEDs) based on such pyridine‐containing [3+2+1] iridium (III) dopants have exhibited maximum external quantum efficiencies (EQEmax) and current efficiency (CE) of 17.3% and 42.3 cd A–1, respectively. To note, very small efficiency roll‐off value from 4.3% to 19.7% is achieved at the luminance level of 1000 cd m–2. The well‐balanced electron and hole injection currents, the short lifetime of excited excitons, and wide recombination zone by leveraging the obtained iridium (III) dopants and exciplex co‐host have greatly decreased the accumulation of triplet excitons at the high luminescence level, leading to dramatically reduced efficiency roll‐off. It is anticipated that this work provides new insights into the design of saturated‐blue‐emitting iridium (III) complexes with reduced efficiency roll‐off in their fabricated OLEDs. [ABSTRACT FROM AUTHOR]

Blue fluorescent materials are an essential part of commercial OLED displays and lightings. However, the market lacks highly efficient, short-emission wavelength blue fluorescent materials. Herein, two new blue fluorescent materials, SAFPI-3 and SAFPI-2, are developed based on a phenanthroimidazole derivative and spiro fluorene triphenylamine by replacing the substitution sites, which tactfully utilize the spatial configuration of the molecules to achieve higher external quantum efficiency and a shorter emission wavelength at the same time. Furthermore, the versatility of SAFPI-3 and SAFPI-2 can be demonstrated as non-doped emitters for blue OLEDs and as the hosts of yellow phosphorescent OLEDs, which have achieved a high external quantum efficiency of 23.98% with extremely low-efficiency roll-off. [Display omitted] • Two novel blue fluorescent isomers are developed. • SAFPI-3 -based non-doped OLED achieves a high EQE of 4.99% with EL emission peak at 432 nm. • OLED using SAFPI-3 as host obtains high EQE of 23.98% with negligible efficiency roll-off. [ABSTRACT FROM AUTHOR]

We report two yellow-emitting cyclometalated gold(III) complexes serving as phosphorescent dopants for high-brightness solution-processed white organic light-emitting devices (WOLEDs). Dichromatic WOLEDs consisting of our newly synthesized Au–Y or Au–wY for yellow emission in combination with FIrpic for blue emission have been studied. Notably, white emissions in terms of Commission Internationale de L'Eclairage coordinates of (0.31, 0.39) and (0.40, 0.47) and color rendering indices of 66 and 69 have been accomplished with Au–Y- and Au–wY-based WOLEDs. In addition, current efficiencies of 26.0 and 25.7 cd/A corresponding to external quantum efficiencies of 11.0% and 10.5% are achieved and can be maintained at 19.8 and 25.3 cd/A at a high brightness level of 10,000 cd/m2 for these devices. Such high-performance WOLEDs in terms of small efficiency roll-offs over a wide brightness range are believed to be due to the use of gold(III) complexes with very short-lived emission lifetimes of ~ 1 μs, high photoluminescence quantum yields of up to 86% and broad yellow emission bandwidths of up to 107 nm. This study opens up the possibility of using solution-processable cyclometalated organogold(III) complexes with short-lived emissive excited states for the fabrication of WOLEDs, especially for high-brightness applications. [ABSTRACT FROM AUTHOR]