1D Tellurium Nanostructures: Photothermally Assisted Morphology‐Controlled Synthesis and Applications in Preparing Functional Nanoscale Materials

A facile visible‐light‐assisted solution‐phase approach has been successfully developed to synthesize trigonal Te 1D nanostructures. By varying the relative amount of H₂TeO₃ and water‐soluble polymers, wirelike, beltlike, tubular Te, and Te nanoparticle‐joined 1D aggregates, as well as a novel thorny 1D assembly of Te nanothreads can be synthesized on a large scale. The diameter of the Te nanowires can be modulated by controlling the nucleation and growth process through modulation of the pH value of the reaction mixture. It is believed that the light irradiation and thermal effect play a significant role in this photothermally assisted technique. We have shown that the Te nanowires can be used as a template to prepare Pt–Te nanochains, where the composition of Pt in the Pt–Te 1D products can be modulated by adjusting the ratio of the Te nanowires and Pt salts. Preliminary optical investigations reveal that blue–violet emission of Te nanowires can be enhanced by the formation of defects or dislocations in the Te region through the galvanic replacement reaction between Te nanowires and H₂PtCl₆. In addition, we demonstrate that Te 1D nanostructures can be utilized to prepare Te at carbon‐rich nanocables and carbonaceous nanotubes. Te–Pt at carbon‐rich nanocables can also be fabricated using Te–Pt nanochains as the template. These Pt–Te nanochains and carbonaceous nanostructures are expected to find wide applications in electrochemistry, catalysis, fuel cells, sensors, and other fields. Furthermore, the successful preparation of Te 1D nanostructures with abundant shapes, Pt–Te nanochains, and their carbonaceous composite nanomaterials will offer great opportunities to explore the dependence of novel properties of nanomaterials on their morphology and composition, regulate the photoconductivity of semiconductors, and also be essential for the manufacture of potential optoelectronic devices.     

“Ship‐in‐a‐Bottle” Growth of Noble Metal Nanostructures

Noble metal nanostructures are grown inside hollow mesoporous silica microspheres using “ship‐in‐a‐bottle” growth. Small Au seeds are first introduced into the interior of the hollow microspheres. Au nanorods with synthetically tunable longitudinal plasmon wavelengths and Au nanospheres are obtained through seed‐mediated growth within the microspheres. The encapsulated Au nanocrystals are further coated with Pd or Pt shells. The microsphere‐encapsulated bimetallic core/shell nanostructures can function as catalysts. They exhibit high catalytic performance and their stability is superior to that of the corresponding unencapsulated core/shell nanostructures in the catalytic oxidation of o‐phenylenediamine with hydrogen peroxide. Therefore, these hollow microsphere‐encapsulated metal nanostructures are promising as recoverable and efficient catalysts for various liquid‐phase catalytic reactions.     

Study of Configuration Differentia and Highly Efficient,Deep‐Blue,Organic Light‐Emitting Diodes Based on Novel Naphtho[1,2‐d]imidazole Derivatives

Two novel naphtho[1,2‐d]imidazole derivatives are developed as deep‐blue, light‐emitting materials for organic light‐emitting diodes (OLEDs). The 1H‐naphtho[1,2‐d]imidazole based compounds exhibit a significantly superior performance than the 3H‐naphtho[1,2‐d]imidazole analogues in the single‐layer devices. This is because they have a much higher capacity for direct electron‐injection from the cathode compared to their isomeric counterparts resulting in a ground‐breaking EQE (external quantum efficiency) of 4.37% and a low turn‐on voltage of 2.7 V, and this is hitherto the best performance for a non‐doped single‐layer fluorescent OLED. Multi‐layer devices consisting of both hole‐ and electron‐transporting layers, result in identically excellent performances with EQE values of 4.12–6.08% and deep‐blue light emission (Commission Internationale de l'Eclairage (CIE) y values of 0.077–0.115) is obtained for both isomers due to the improved carrier injection and confinement within the emissive layer. In addition, they showed a significantly better blue‐color purity than analogous molecules based on benzimidazole or phenanthro[9,10‐d]imidazole segments.     

One‐Dimensional Metal‐Oxide Nanostructures: Recent Developments in Synthesis,Characterization, and Applications

1D metal‐oxide nanostructures have attracted much attention because metal oxides are the most fascinating functional materials. The 1D morphologies can easily enhance the unique properties of the metal‐oxide nanostructures, which make them suitable for a wide variety of applications, including gas sensors, electrochromic devices, light‐emitting diodes, field emitters, supercapacitors, nanoelectronics, and nanogenerators. Therefore, much effort has been made to synthesize and characterize 1D metal‐oxide nanostructures in the forms of nanorods, nanowires, nanotubes, nanobelts, etc. Various physical and chemical deposition techniques and growth mechanisms are exploited and developed to control the morphology, identical shape, uniform size, perfect crystalline structure, defects, and homogenous stoichiometry of the 1D metal‐oxide nanostructures. Here a comprehensive review of recent developments in novel synthesis, exceptional characteristics, and prominent applications of one‐dimensional nanostructures of tungsten oxides, molybdenum oxides, tantalum oxides, vanadium oxides, niobium oxides, titanium oxides, nickel oxides, zinc oxides, bismuth oxides, and tin oxides is provided.     

Inorganic and Hybrid Organo‐Metal Perovskite Nanostructures: Synthesis,Properties, and Applications

Hybrid perovskite and all‐inorganic perovskite have attracted much attention in recent years owing to their successful use in the photovoltaic field. Usually the perovskite is used in its bulk form, although recently, perovskites' nanocrystalline form has received increased attention. Recent developments in the evolving research field of nanomaterial‐based perovskite are reviewed. Both hybrid organic‐inorganic and all‐inorganic perovskite nanostructures are discussed, as well as approaches to tune the optical properties by controlling the size and shape of perovskite nanostructures. In addition, chemical modifications can change the perovskite nanostructures' band‐gap, similar to their bulk counterpart. Several applications, including light‐emitting diodes, lasers, and detectors, demonstrate the latent potential of perovskite nanostructures.     

A New Strategy toward “Simple” Water‐Soluble AIE Probes for Hypoxia Detection

Hypoxia‐responsive fluorescent probes have emerged as a novel scaffold for tumor diagnosis. However, dilemma often exists between simple synthesis and high water solubility in traditional probes. Owing to the intrinsic property of N‐oxides, herein, a new strategy is proposed to design and synthesize probes for in vitro hypoxia imaging. Equipped with tetraphenylethene (TPE), the N‐oxides exhibit aggregation‐induced emission characteristics and emit no light in aqueous solutions. Interestingly, the N‐oxides can be reduced by ferrous ions in different rates. The aggregation of the resulting hydrophobic TPE residues restricts the intramolecular motions of the molecules, which “turns‐on” their fluorescence. The N? O covalent bond of one molecule can be specifically cleaved by cellular reductase overexpressed under hypoxic conditions, and thus turn‐on hypoxia imaging in vitro is achieved. The new strategy to design hypoxia imaging probes is extremely valuable and has great potential for application in tumor diagnosis.     

Comment on “Rapid Assembly of Small Materials Building Blocks (Voxels) into Large Functional 3D Metamaterials”

In their Progress Report, Hahn et al. assessed the state‐of‐the‐art of 3D printing but excluded temporally focused two‐photon polymerization (2PP) from the comparison because they concluded that it does not represent a full 3D printing capability. This comment highlights the flaws in their scientific arguments, clarifies the misinterpretation of private communications, and shows that 3D structures with distinct z‐layers can be printed using temporally focused 2PP.     

Stimuli‐Directing Self‐Organized 3D Liquid‐Crystalline Nanostructures: From Materials Design to Photonic Applications

3D photonic nanostructures with desirable functionalities in the visible light region and beyond have been recently given vast and increasing attentions because of the ability to control or confine electromagnetic waves in all three dimensions. Although substantial progress has been made in fabricating 3D nanostructures by means of lithography and nanotechnology, various bottlenecks still need to be overcome, and developing soft 3D stimuli‐directed nanostructures with tailored properties remains a challenging but exciting work. In this context, soft nanotechnology—i.e., exploiting self‐organized soft materials in nanotechnology—is emerging as a vibrant and burgeoning field of research in the bottom‐up nanofabrication of intelligent stimuli‐driven 3D photonic materials and devices. Liquid‐crystalline materials undoubtedly represent such a marvelous dynamic system that combines the liquid‐like fluidity and crystal‐like ordering from molecular to macroscopic material levels. Importantly, being “soft” makes the materials responsive to various stimuli such as temperature, light, mechanical force, and electric and magnetic fields as well as chemical and electrochemical reactions, resulting in a fascinating tunability of dynamic photonic bandgaps in the 3D nanostructure that provides numerous opportunities in all‐optical integrated circuits and next‐generation communication systems. Here, the development of 3D photonic nanostructures is reviewed, culminating with perspectives for the future scope and challenges of these emerging soft 3D photonic nanostructures towards device applications.     

CdIn2S4 Nanotubes and “Marigold” Nanostructures: A Visible‐Light Photocatalyst

Nanostructured photocatalysts with high activity are sought for solar production of hydrogen. Spinel semiconductors with different nanostructures and morphologies have immense importance for photocatalytic and other potential applications. Here, a chemically stable cubic spinel nanostructured CdIn₂S₄ prepared by a facile hydrothermal method is reported as a visible‐light driven photocatalyst. A pretty, marigold‐like morphology is observed in aqueous‐mediated CdIn₂S₄, whereas nanotubes of good crystallinity, 25 nm in diameter, are obtained in methanol‐mediated CdIn₂S₄. The aqueous‐ and methanol‐mediated CdIn₂S₄ products show excellent photocatalytic activity compared to other organic mediated samples, and this is attributed to their high degree of crystallinity. The CdIn₂S₄ photocatalyst gives quantum yields of 16.8 % (marigold‐like morphology) and 17.1 % (nanotubes) at 500 nm, respectively, for the H₂ evolution reaction. The details of the characteristics of the photocatalyst, such as crystal and band structure, are reported. Considering the importance of hydrogen energy, CdIn₂S₄ will be an excellent candidate as a catalyst for “photohydrogen” production under visible light. Being a nanostructured chalcogenide semiconductor, CdIn₂S₄ will have other potential prospective applications, such as in solar cells, light‐emitting diodes, and optoelectronic devices.     

Deep‐Blue Phosphorescent Ir(III) Complexes with Light‐Harvesting Functional Moieties for Efficient Blue and White PhOLEDs in Solution‐Process

The photoluminescence (PL) efficiency of emitters is a key parameter to accomplish high electroluminescent performance in phosphorescent organic light‐emitting diodes (PhOLEDs). With the aim of enhancing the PL efficiency, this study designs deep‐blue emitting heteroleptic Ir(III) complexes (tBuCN‐FIrpic, tBuCN‐FIrpic‐OXD, and tBuCN‐FIrpic‐mCP) for solution‐processed PhOLEDs by covalently attaching the light‐harvesting functional moieties (mCP‐Me or OXD‐Me) to the control Ir(III) complex, tBuCN‐FIrpic. These Ir(III) complexes show similar deep‐blue emission peaks around 453, 480 nm (298 K) and 447, 477 nm (77 K) in chloroform. tBuCN‐FIrpic‐mCP demonstrates higher light‐harvesting efficiency (142%) than tBuCN‐FIrpic‐OXD (112%), relative to that of tBuCN‐FIrpic (100%), due to an efficient intramolecular energy transfer from the mCP group to the Ir(III) complex. Accordingly, the monochromatic PhOLEDs of tBuCN‐FIrpic‐mCP show higher external quantum efficiency (EQE) of 18.2% with one of the best blue coordinates (0.14, 0.18) in solution‐processing technology. Additionally, the two‐component (deep‐blue:yellow‐orange), single emitting layer, white PhOLED of tBuCN‐FIrpic‐mCP shows a maximum EQE of 20.6% and superior color quality (color rendering index (CRI) = 78, Commission Internationale de L'Eclairage (CIE) coordinates of (0.353, 0.352)) compared with the control device containing sky‐blue:yellow‐orange emitters (CRI = 60, CIE coordinates of (0.293, 0.395)) due to the good spectral coverage by the deep‐blue emitter.     

Synthesis,Structure, Electronic State,and Luminescent Properties of Novel Blue‐Light‐Emitting Aryl‐Substituted 9,9‐Di(4‐(di‐p‐tolyl)aminophenyl)fluorenes

Novel blue‐light‐emitting fluorene derivatives 5a–c and 7a–c containing bulky and highly emissive groups, namely pyrene, 10‐phenylanthracene‐9‐yl and 10‐(4′‐diphenylaminophenyl)anthracene‐9‐yl groups, as well as hole‐injecting/transporting triarylamines were synthesized. Single crystals of compounds 5a , 5c , 7a , and 7c were grown and their crystal structures were determined by X‐ray diffraction. The four fluorene derivatives have nonplanar molecular structures, which reduce the intermolecular interaction and the likelihood of molecular aggregation or excimer formation. No unwanted long‐wavelength emission was observed in the photoluminescence (PL) spectra of the 5a–c and 7a–c thin films. Their PL spectra reveal excellent thermal stability after annealing treatment under air and ambient light. All of the six compounds show high fluorescence quantum yields and outstanding thermal stabilities. The 2‐aryl and 2,7‐diaryl substituents at the fluorene molecule have a significant effect on the photophysical properties and the thermal characteristics. The six compounds show almost the same energy levels for the highest occupied molecular orbitals (HOMOs) of about ?5.20 eV, which allows effective hole injection. The C2‐ and C7‐aryl substituents play a relatively less‐important role in the HOMO energy levels, which depend mainly on the triphenylamino groups at the C9 position. The molecular orbitals, excitation energy, and emission energy were calculated to explain the real origin of their photophysical characteristics. The HOMOs are mainly localized on the triphenylamino groups at the C9 position, while the lowest unoccupied molecular orbitals (LUMOs) have a significant orbital density at the C2‐ and/or C7‐aryl substituents. Pure‐blue‐light‐emitting diodes based on 2,7‐diaryl‐9,9‐di(triarylamino)fluorenes were fabricated.     

Utilizing a Spiro TADF Moiety as a Functional Electron Donor in TADF Molecular Design toward Efficient “Multichannel” Reverse Intersystem Crossing

Designing thermally activated delayed fluorescence (TADF) materials with an efficient reverse intersystem crossing (RISC) process is regarded as the key to actualize efficient organic light‐emitting diodes (OLEDs) with low efficiency roll‐off. Herein, a novel molecular design strategy is reported where a typical TADF material 10‐phenyl‐10H, 10′H‐spiro[acridine‐9, 9′‐anthracen]‐10′‐one (ACRSA) is utilized as a functional electron donor to design TADF materials of 2,4,6‐triphenyl‐1,3,5‐triazine(TRZ)‐p‐ACRSA and TRZ‐m‐ACRSA. It is unique that the intramolecular charge transfer of the ACRSA moiety and the intramolecular and through‐space intermolecular charge transfer between the TRZ and ACRSA moieties, provide a “multichannel” effect to enhance the rate of the reverse intersystem crossing process (k_risc) exceeding 10^?6 s^?1. TADF OLEDs based on TRZ‐p‐ACRSA as an emitter show a maximum external quantum efficiency (EQE) of 28% with reduced efficiency roll‐off (EQEs of 27.5% and 22.1% at 100 and 1000 cd m^?2, respectively). Yellow phosphorescent OLEDs utilizing TRZ‐p‐ACRSA as a host material show record‐high EQE of 25.5% and power efficiency of 115 lm W^?1, while phosphorescent OLEDs based on TRZ‐m‐ACRSA show further lower efficiency roll‐off with EQEs of 25.2%, 24.3%, and 21.5% at 100, 1000, and 10 000 cd m^?2, respectively.     

From “Face‐Saving” to “Cost Saving”: Encouraging and Promoting Business Mediation in Asia

The past decade has witnessed a surge in efforts to institutionalize and popularize business mediation as an alternative to litigation in Asia. For example, the anticipated establishment of the Singapore International Mediation Centre ( bit.ly/1rqO845 ) and the existence of the Hong Kong Mediation Council ( bit.ly/1vQWqGS ) and Financial Dispute Resolution Centre ( bit.ly/1skmJpO ), evince an increasing demand for mediation in Asia. It has been just over two years since the Hong Kong SAR adopted a Mediation Ordinance ( bit.ly/1pUVDRe ), which entered into effect on January 1, 2013, signaling that states are becoming aware of the need to regulate mediation.     

Vibration‐Induced Emission (VIE) of N,N′‐Disubstituted‐Dihydribenzo[a,c]phenazines: Fundamental Understanding and Emerging Applications

Organic fluorophores with dual‐emission and large Stokes shifts are attracting great attention due to their importance in fundamental research and technique applications. This Progress Report gives an account on how a novel luminescence mechanism termed vibration‐induced emission (VIE) is established. The VIE mechanism is coined for the rationalization of an alterable dual emission of V‐shaped N,N′‐disubstituded‐dihydribenzo[a,c]phenazines (DHPs), which are originated from a bent‐to‐planar vibration and the reverse in the excited state. The validation of the VIE mechanism is highlighted, such as the work reporting the utilization of chemically‐locked strategy to snapshot the excited‐state planarization of DHPs, and the application of the approach of steric hindrance‐induced planarization to tune the ground‐state geometry of DHPs. Moreover, the emerging applications of this VIE concept in photoelectric and biomedical disciplines are summarized. Additionally, further development of the VIE systems as well as the remaining challenges are prospected. This report could arouse wide interest from various fields to the specific area of VIE, which would not only broaden the VIE territory but also enlarge the scope of advanced functional materials.     

Response to Comment on “Prediction of Novel p‐Type Transparent Conductors in Layered Double Perovskites: A First‐Principles Study”

The search for high‐performance p‐type transparent conductors is crucial to many emerging optoelectronic applications. Motivated by the pioneer predictions of the existence of intrinsic p‐type conductivity in several wide‐gap layered halide double perovskites, Hu et al. synthesize the Cs₄CdSb₂Cl₁₂ compound, but fail to observe the p‐type conductivity. They argue that the different conclusion is mostly due to the chemical potential boundary overestimation and bandgap underestimation in the initial calculations. In this study, based on the additional calculations, it is demonstrated that these two factors raised by Hu et al. will not affect the major conclusions, although the pinned Fermi level (E_F‐pin) can slightly be changed. Importantly, it is found that the different conclusion obtains by Xu et al. and Hu et al. is mostly due to the different crystal phases adopted, which can have a big impact on the calculated E_F‐pin positions and the resulting p‐type performance. Finally, besides the careful control of growth conditions for reaching the ideal p‐type chemical potential regions, it is suggested that a moderate strain/pressure or fast quenching may be further adopted to enhance the p‐type conductivity in Cs₄CdSb₂Cl₁₂ and other similar compounds for better experimental observations.     

Solid‐Phase Synthesis of Molecularly Imprinted Polymer Nanoparticles with a Reusable Template–“Plastic Antibodies”

Molecularly imprinted polymers (MIPs) are generic alternatives to antibodies in sensors, diagnostics, and separations. To displace biomolecules without radical changes in infrastructure in device manufacture, MIPs should share their characteristics (solubility, size, specificity and affinity, localized binding domain) whilst maintaining the advantages of MIPs (low‐cost, short development time, and high stability) hence the interest in MIP nanoparticles. Herein, a reusable solid‐phase template approach is reported (fully compatible with automation) for the synthesis of MIP nanoparticles and their precise manufacture using a prototype automated UV photochemical reactor. Batches of nanoparticles (30–400 nm) with narrow size distributions imprinted with: melamine (d = 60 nm, K_d = 6.3 × 10^?8 M ), vancomycin (d = 250 nm, K_d = 3.4 × 10^?9 M ), a peptide (d = 350 nm, K_d = 4.8 × 10^?8 M ) and proteins have been produced. The instrument uses a column packed with glass beads, bearing the template. Process parameters are under computer control, requiring minimal manual intervention. For the first time, the reliable re‐use of molecular templates is demonstrated in the synthesis of MIPs (≥30 batches of nanoMIPs without loss of performance). NanoMIPs are produced template‐free and the solid‐phase acts both as template and affinity separation medium.