Search

Understanding structural responses of metal–organic frameworks (MOFs) to external stimuli such as the inclusion of guest molecules and temperature/pressure has gained increasing attention in many applications, for example, manipulation and manifesto smart materials for gas storage, energy storage, controlled drug delivery, tunable mechanical properties, and molecular sensing, to name but a few. Herein, neutron and synchrotron diffractions along with Rietveld refinement and density functional theory calculations have been used to elucidate the responsive adsorption behaviors of defect-rich Zr-based MOFs upon the progressive incorporation of ammonia (NH3) and variable temperature. UiO-67 and UiO-bpydc containing biphenyl dicarboxylate and bipyridine dicarboxylate linkers, respectively, were selected, and the results establish the paramount influence of the functional linkers on their NH3 affinity, which leads to stimulus-tailoring properties such as gate-controlled porosity by dynamic linker flipping, disorder, and structural rigidity. Despite their structural similarities, we show for the first time the dramatic alteration of NH3 adsorption profiles when the phenyl groups are replaced by the bipyridine in the organic linker. These molecular controls stem from controlling the degree of H-bonding networks/distortions between the bipyridine scaffold and the adsorbed NH3 without significant change in pore volume and unit cell parameters. Temperature-dependent neutron diffraction also reveals the NH3-induced rotational motions of the organic linkers. We also demonstrate that the degree of structural flexibility of the functional linkers can critically be affected by the type and quantity of the small guest molecules. This strikes a delicate control in material properties at the molecular level.

Convenient transportation and the large flow of residents in the city give rise to the wide spread of COVID-19. Data collection plays a crucial role in determining the effectiveness of the control of the pandemic. The pandemic is not only a serious problem in large cities, but also hitting medium-sized cities. Macau is a typical medium-sized city where the pandemic has been under effective control with comprehensive data collection. This thesis will conduct in-depth research on the collection and application of the statistics about COVID-19 in Macau. Macau collects data through the border, incorporating NAT (nucleic acid testing) data and health codes into daily-used mobile applications, which features a network with real-time updates and sharing. This thesis will connect to the construction of smart cities to provide ideas for handling large-scale public health issues in medium-sized cities.

Altering the exposed facet of CeO2 nanocrystallites and hence the control of surface chemistry on the nano level have been shown to significantly change their performances in various catalytic reac...

Acute graft versus host disease (aGVHD) is a rare, but severe complication of liver transplantation (LT). It is caused by the activation of donor immune cells in the graft against the host shortly after transplantation, but the contributing pathogenic factors remain unclear. Here we show that human T cell lymphotropic virus type I (HTLV-1) infection of donor T cells is highly associated with aGVHD following LT. The presence of HTLV-1 in peripheral blood and tissue samples from a discovery cohort of 7 aGVHD patients and 17 control patients is assessed with hybridization probes (TargetSeq), mass cytometry (CyTOF), and multiplex immunohistology (IMC). All 7 of our aGVHD patients display detectable HTLV-1 Tax signals by IMC. We identify donor-derived cells based on a Y chromosome-specific genetic marker, EIF1AY. Thus, we confirm the presence of CD4+Tax+EIF1AY+ T cells and Tax+CD68+EIF1AY+ antigen-presenting cells, indicating HTLV-1 infection of donor immune cells. In an independent cohort of 400 patients, we verify that HTLV-1 prevalence correlates with aGVHD incidence, while none of the control viruses shows significant associations. Our findings thus provide new insights into the aetio-pathology of liver-transplantation-associated aGVHD and raise the possibility of preventing aGVHD prior to transplantation.

Biomass rapid pyrolysis technology is easy to implement in continuous production and industrial application, and has become one of the leading technologies in the field of world renewable energy development. Agricultural and forestry waste is an important resource of renewable energy in China. In general, abandoned leaves in forest areas cause serious waste of resources. Its utilization may help to settle the problems of energy deficiency and environment pollution. In this study, Aesculus chinensis Bunge leaves (A. Bunge) are used as the research object to study the pyrolysis and extract. The results showed that there are a lot of bioactive components in A. Bunge leaves extract, including acetamide, 5-hydroxymethylfurfural, R-limonene, d-mannose, and dihydroxyacetone. The active components of A. Bunge leaves supply scientific evidence for the exploration and exploitation of this plant. The pyrolysis products of A. Bunge leaves are rich in organic acids, aldehydes, and ketones, which means that A. Bunge leaves can be used as a crude material for the manufacturing of bio-oil or bio-fuel. The pyrolysis products include batilol, pregnenolone, benzoic acid, butyrolactone, and propanoic acid, which can be used in biological medicine, chemical crude materials, and industrial raw material reagents. Therefore, A. Bunge leaves can be used as a good crude material for bio-oil or biofuel production. Combining A. Bunge leaves and fast pyrolysis methods can effectively solve the problem of forestry and agricultural residues in the future.

Biomass has been recognized as the most common source of renewable energy. In recent years, researchers have paved the way for a search for suitable biomass resources to replace traditional fossil fuel energy and provide high energy output. Although there are plenty of studies of biomass as good biomaterials, there is little detailed information about Staphylea holocarpa wood (S. holocarpa) as a potential bio-oil material. The purpose of this study is to explore the potential of S. holocarpa wood as a bio-oil. Nanocatalyst cobalt (II) oxide (Co3O4) and Nickel (II) oxide (NiO) were used to improve the production of bio-oil from S. holocarpa wood. The preparation of biofuels and the extraction of bioactive drugs were performed by the rapid gasification of nanocatalysts. The result indicated that the abundant chemical components detected in the S. holocarpa wood extract could be used in biomedicine, cosmetics, and biofuels, and have a broad industrial application prospect. In addition, nanocatalyst cobalt tetraoxide (Co3O4) could improve the catalytic cracking of S. holocarpa wood and generate more bioactive molecules at high temperature, which is conducive to the utilization and development of S. holocarpa wood as biomass. This is the first time that S. holocarpa wood was used in combination with nanocatalysts. In the future, nanocatalysts can be used to solve the problem of sustainable development of biological resources.

Transition metal doped chalcogenides are one of the most important classes of catalysts that have been attracting increasing attention for petrochemical and energy related chemical transformations due to their unique physiochemical properties. For practical applications, achieving maximum atom utilization by homogeneous dispersion of metals on the surface of chalcogenides is essential. Herein, we report a detailed study of a deposition method using thiourea coordinated transition metal complexes. This method allows the preparation of a library of a wide range of single atoms including both noble and non-noble transition metals (Fe, Co, Ni, Cu, Pt, Pd, Ru) with a metal loading as high as 10 wt % on various ultrathin 2D chalcogenides (MoS2, MoSe2, WS2 and WSe2). As demonstrated by the state-of-the-art characterization, the doped single transition metal atoms interact strongly with surface anions and anion vacancies in the exfoliated 2D materials, leading to high metal dispersion in the absence of agglomeration. Taking Fe on MoS2 as a benchmark, it has been found that Fe is atomically dispersed until 10 wt %, and beyond this loading, formation of coplanar Fe clusters is evident. Atomic Fe, with a high electron density at its conduction band, exhibits a superior intrinsic activity and stability in CO2 hydrogenation to CO per Fe compared to corresponding surface Fe clusters and other Fe catalysts reported for reverse water–gas-shift reactions.

Plasmonic antennas and metasurfaces can effectively control light-matter interactions, and this facilitates a deterministic design of optical materials properties, including structural color. However, these optical properties are generally fixed after synthesis and fabrication, while many modern-day optics applications require active, low-power, and nonvolatile tuning. These needs have spurred broad research activities aimed at identifying materials and resonant structures capable of achieving large, dynamic changes in optical properties, especially in the challenging visible spectral range. In this work, we demonstrate dynamic tuning of polarization-dependent gap plasmon resonators that contain the electrochromic oxide WO3. Its refractive index in the visible changes continuously from n = 2.1 to 1.9 upon electrochemical lithium insertion and removal in a solid-state device. By incorporating WO3 into a gap plasmon resonator, the resonant wavelength can be shifted continuously and reversibly by up to 58 nm with less than 2 V electrochemical bias voltage. The resonator can remain in a tuned state for tens of minutes under open circuit conditions.

The high activity of nanocrystallites is commonly attributed to the terminal high-energy facets. However, we demonstrate that the high activity of the anatase TiO2(001) facet in photocatalytic H2 evolution is not due to its high intrinsic surface energy, but local electronic effects created by surface features on the facet.

Li X FePO 4 (0 X FePO 4 exhibits a nonequilibrium solid solution behavior at elevated cycling rates. This article reviews recent research on nonequilibrium solid solution in Li X FePO 4 ; these insights have been largely enabled by operando characterization techniques. Such studies have not only unambiguously confirmed the existence of this solid solution, but also show how surface reaction and diffusion kinetics ultimately affect phase separation and other spatially nonuniform lithiation and delithiation behavior.

TiO2-based powder materials have been widely studied as efficient photocatalysts for water splitting due to their low cost, photo-responsivity, earthly abundance, chemical and thermal stability, etc. In particular, the recent breakthrough of nitrogen-doped TiO2, which enhances the presence of structural defects and dopant impurities at elevated temperatures, exhibits an impressive visible-light absorption for photocatalytic activity. Although their electronic and optical properties have been extensively studied, the structure-activity relationship and photocatalytic mechanism remain ambiguous. Herein, we report an in-depth structural study of rutile, anatase and mixed phases (commercial P25) with and without nitrogen-doping by variable-temperature synchrotron X-ray powder diffraction. We report that an unusual anisotropic thermal expansion of the anatase phase can reveal the intimate relationship between sub-surface oxygen vacancies, nitrogen-doping level and photocatalytic activity. For highly doped anatase, a new cubic titanium oxynitride phase is also identified which provides important information on the fundamental shift in absorption wavelength, leading to excellent photocatalysis using visible light., Nitrogen-doped TiO2 exhibits improved photocatalytic water-splitting activity partially due to enhanced oxygen vacancy formation. Here, authors demonstrate the temperature-dependent lattice distortion of oxygen vacancies, and identify the presence of a titanium oxynitride phase in high activity catalysts.

Solar light-driven water splitting provides a promising way to store and use abundant solar energy in the form of gaseous hydrogen which is the cleanest chemical fuel for mankind; therefore this field has been attracting increasing attention over the past decades. The fundamental steps for efficient photocatalyst for water splitting include uptake of photons of targeted energy range by appropriate electronic band structure, excited electrons and holes (excitons) migration, as well as recombination and selective conversion excited electrons for H+ reduction to H2 and holes and OH− to O2 on catalyst surface. Each step if not efficiently taken place could hamper the overall photocatalytic activity. Numerous semiconductors with appropriate bandgaps have mainly been developed as candidates for effective solar energy capture, whereas at present, their low quantum efficiency still remains as the major obstacle in further applications. In this minireview, we will disentangle the progress to develop photocatalysts with good photon uptake from photocatalytic water splitting performance. In accordance with the thermodynamic and kinetic considerations of the photocatalytic water splitting reaction, different strategies for improving the fundamental processes have been briefly reviewed. Some recent advances in facilitating charge carriers separation have also been presented. Photocatalytic water splitting at elevated temperatures is emphasized as a novel approach to suppress photo-excitons recombination on catalyst surface owing to adsorption of enhanced concentration of ionic species including H+ and OH− to create their local polarization to the excitons. Stronger polarization to hinder the excitons recombination can also be obtained by using polar-faceted support materials to the active phase of semiconductor. It is clearly demonstrated in this minireview that such high temperature–promoted photocatalytic water splitting systems could open up a new direction and provide a new innovation to this field.

Phase transformations driven by compositional change require mass flux across a phase boundary. In some anisotropic solids, however, the phase boundary moves along a non-conductive crystallographic direction. One such material is LiXFePO4, an electrode for lithium-ion batteries. With poor bulk ionic transport along the direction of phase separation, it is unclear how lithium migrates during phase transformations. Here, we show that lithium migrates along the solid/liquid interface without leaving the particle, whereby charge carriers do not cross the double layer. X-ray diffraction and microscopy experiments as well as ab initio molecular dynamics simulations show that organic solvent and water molecules promote this surface ion diffusion, effectively rendering LiXFePO4 a three-dimensional lithium-ion conductor. Phase-field simulations capture the effects of surface diffusion on phase transformation. Lowering surface diffusivity is crucial towards supressing phase separation. This work establishes fluid-enhanced surface diffusion as a key dial for tuning phase transformation in anisotropic solids.

Here, the abilities of carbon nanocages (C60, C72 and C84) as anode electrodes in lithium-ion battery (LIB) and potassium-ion battery (KIB) were examined by theoretical method. The effects of adsorbed Gallium oxide (GaO) and Tin dioxide (SnO2) on performances of C60, C72 and C84 as anode electrodes in LIB and KIB were investigated. The cell voltage (Vcell), Gibbs free energy (Gad), band gap energy (EHLG) and charge transferred (q) of studied complexes were calculated. Results indicated that Gibbs free energies of adsorption of GaO on C60, C72 and C84 nanocages were higher than SnO2. The band gap energy of GaO-C84 was lower than GaO-C60 and GaO-C72. Results showed that adsorbed SnO2 and GaO can increase the |q|, |Gad| and Vcell values of C60, C72 and C84 nanocages, significantly. Finally, the C84-SnO2 as novel anode electrodes in LIB and KIB with the highest Vcell was proposed to use in electrical machines.

In this work, the organic light-emitting diodes (OLEDs) based on Alq3 are fabricated. In order to make clear the transport mechanism of carriers in organic light-emitting devices at low temperature, detailed electroluminescence transient response and the current-voltage–luminescence (I–V–L) characteristics under different temperatures in those OLEDs are investigated. It founds that the acceleration of brightness increases with increasing temperature is maximum when the temperature is 200 K and it is mainly affected by the electron transport layer (Alq3). The MoO3 injection layer and the electroluminescent layer have great influence on the delay time when the temperature is 200 K. Once the temperature is greater than 250 K, the delay time is mainly affected by the MoO3 injection layer. On the contrary, the fall time is mainly affected by the electroluminescent material. The Vf is the average growth rate of fall time when the temperature increases 1 K which represents the accumulation rate of carriers. The difference between Vf caused by the MoO3 injection layer is 0.52 us/K and caused by the electroluminescent material Ir(ppy)3 is 0.73 us/K.

Space charge capacitance and the physical mechanism of negative capacitance in organic light-emitting diodes (OLEDs) by transient current response analysis are investigated for the first time. Space charge capacitance is found to be a fixed value as voltage increases for each device. The inflection points in capacitance–voltage curves correspond to carrier injection, transportation and combination processes in organic layers. A negative capacitance effect at low frequency relates to the internal accumulated carrier state in the OLEDs. The nonsynchronicity between the phases of the internal accumulated carriers’ states changing and the small alternating current leads to electric field reversal. Only the electric field reversal at low frequency results in a negative capacitance effect.

Pb–PbO2, Pb–Co3O4 and Pb–Co3O4–PbO2 composite inert anodes were prepared by vacuum hot pressing technique from the mixtures of lead powders, Co3O4 and PbO2 particles in a fixed mould. The influences of heating temperatures and particles doping on the properties of the composite inert anodes were researched. The surface microstructures, phase structures and electrochemical properties were measured by X-ray diffraction (XRD), scanning electronic microscopy (SEM), energy dispersive spectrometer (EDS), anodic polarization curves (AP), cyclic voltammetry curves (CV), Tafel polarization curves and electrochemical impedance spectroscopy (EIS). The results showed that the uniform distributions of Co3O4 and PbO2 as the second phase particles in the composite inert anodes have been obtained by the vacuum hot pressing technique. The lead powders were melted and formed a uniform and compact matrix, in which the morphologies and properties of Co3O4 and PbO2 particles were kept. The electrochemical property and corrosion resistance of the composite inert anodes in a zinc electrowinning simulation solution were improved with the rise of heating temperatures during the vacuum hot pressing, and those were also enhanced by the doping of Co3O4 and PbO2 particles. This method solved the problems of the lower dispersion uniformity of the composite inert anodes prepared by composite electrodeposition or traditional casting technique.

Photocatalytic water splitting is attracting enormous interest for the storage of solar energy but no practical method has yet been identified. In the past decades, various systems have been developed but most of them suffer from low activities, a narrow range of absorption and poor quantum efficiencies (Q.E.) due to fast recombination of charge carriers. Here we report a dramatic suppression of electron-hole pair recombination on the surface of N-doped TiO2 based nanocatalysts under enhanced concentrations of H+ and OH−, and local electric field polarization of a MgO (111) support during photolysis of water at elevated temperatures. Thus, a broad optical absorption is seen, producing O2 and H2 in a 1:2 molar ratio with a H2 evolution rate of over 11,000 μmol g−1 h−1 without any sacrificial reagents at 270 °C. An exceptional range of Q.E. from 81.8% at 437 nm to 3.2% at 1000 nm is also reported. Chemical fuels, produced from light, afford an alternative to fossil fuel, but conversion materials suffer from low photon-to-fuel efficiencies. Here, authors incorporate gold/N-doped TiO2 on MgO surfaces and show enhanced photocatalytic water splitting performances at elevated temperatures.

The slight abuse of lithium ion power batteries is inevitable during the practical charge/discharge process. Herein, we investigated the cycle decay behavior of Li(Ni1/3Co1/3Mn1/3)O2/graphite (NCM/C) high-power battery during slight overcharge (110% SOC) and over-discharge (2 V for lower cut-off voltage). The results show that the cycle life of NCM/C battery is about 1500 cycles at 45 °C, whereas the slight overcharge would markedly accelerate the capacity degradation and shorten the cycle life (only 500 cycles). In contrast, the slight over-discharge causes less damage (about 1300 cycles). A post-mortem study further reveals that the severe aging during overcharge can be mainly ascribed to the capacity loss of the layered oxide cathode material (NCM), followed by an inhomogeneous degradation in the anode. The ex situ XRD results show that the origin of the differing abuse tolerance during overcharge and over-discharge is due to the different crystal structure stability of NCM, which is more unstable in the delithiation state than that in the lithiation state, particularly at an excess delithiation condition corresponding to the overcharge state. Through HR-TEM, it is observed that the NCM suffers from irreversible phase transformation (8–10 nm rock salt phase at surface) even with a slight overcharge. This work provides effective guidance for how to design a voltage control strategy in a battery management system and avoid the capacity decay of NCM/C high-power battery during overcharge and over-discharge application.

Lithium-rich layered transition metal oxide positive electrodes offer access to anion redox at high potentials, thereby promising high energy densities for lithium-ion batteries. However, anion redox is also associated with several unfavorable electrochemical properties, such as open-circuit voltage hysteresis. Here we reveal that in Li1.17–xNi0.21Co0.08Mn0.54O2, these properties arise from a strong coupling between anion redox and cation migration. We combine various X-ray spectroscopic, microscopic, and structural probes to show that partially reversible transition metal migration decreases the potential of the bulk oxygen redox couple by > 1 V, leading to a reordering in the anionic and cationic redox potentials during cycling. First principles calculations show that this is due to the drastic change in the local oxygen coordination environments associated with the transition metal migration. We propose that this mechanism is involved in stabilizing the oxygen redox couple, which we observe spectroscopically to persist for 500 charge/discharge cycles., Lithium ion battery electrodes employing anion redox exhibit high energy densities but suffer from poor cyclability. Here the authors reveal that the voltage of anion redox is strongly affected by structural changes that occur during battery cycling, explaining its unique electrochemical properties.

The minority carrier diffusion length (LD) is a crucial property that determines the performance of light absorbers in photoelectrochemical (PEC) cells. Many transition-metal oxides are stable photoanodes for solar water splitting but exhibit a small to moderate LD, ranging from a few nanometers (such as α-Fe2O3 and TiO2) to a few tens of nanometers (such as BiVO4). Under operating conditions, the temperature of PEC cells can deviate substantially from ambient, yet the temperature dependence of LD has not been quantified. In this work, we show that measuring the photocurrent as a function of both temperature and absorber dimensions provides a quantitative method for evaluating the temperature-dependent minority carrier transport. By measuring photocurrents of nonstoichiometric rutile TiO2–x nanowires as a function of wire radius (19–75 nm) and temperature (10–70 °C), we extract the minority carrier diffusion length along with its activation energy. The minority carrier diffusion length in TiO2–x increases...

© 2017 The Royal Society of Chemistry. The ability to judiciously utilize gel-polymer electrolytes (GPEs) that replace liquid electrolytes is widely recognized as an attractive route to solving the safety concerns of Li-ion batteries (LIBs). In this context, novel LiNi0.8Co0.15Al0.05O2 (NCA)/graphite GPE and NCA/graphite-Si/C GPE batteries with high energy density and excellent electrochemical and safety performances are developed via in situ polymerization of pentaerythritol tetraacrylate (PETEA) in a liquid electrolyte. Notably, the capacity retention of NCA/graphite and NCA/graphite-Si/C GPE batteries after 200 cycles at the discharge rate of 5C is 92.5% and 81.2%, respectively, which are much larger than those implementing liquid electrolytes (i.e., only 55.9% and 51.4%, respectively). Interestingly, the GPE batteries also displayed considerably lower gas production, especially the graphite-Si/C anode battery, and did not undergo a violent combustion during the nail penetration test compared to the liquid electrolyte batteries. The markedly enhanced performances noted above can be attributed to the three-dimensional framework of the GPE which promoted the formation of a very tight protective film on the surface of the electrodes during cycling, thereby inhibiting the cyclable Li consumption and side reactions with the electrolyte. Furthermore, such a protective film effectively retained the structural integrity of the electrodes during the cycling process and reduced the heat reactions between the electrodes and electrolyte.

Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

A stable organic solar cell with structure of ITO/buffer/donor/acceptor/cathode is presented. A thin layer (5 nm) of MoO3-doped CuPc is adopted as the buffer in CuPc/C60 organic heterojunction photovoltaic (PV) solar cells, resulting in two times longer lifetime. The surface morphology of buffer layer plays a decisive role in improving the stability.

An improved evolution from ordered CaCu5-type structure to disordered TbCu7-type structure has been implemented in this work based on the atomic simulation regarding intermetallic compounds NdCo7 and Nd1−xYxCo6.8Zr0.2 (x = 0, 0.2, 0.4, 0.6). The calculated powder patterns, phase stabilities, site preferences and structural properties, including lattice parameters, the shrinkages from 2c to 6l site in 2c layers, the 3g layer deformation, the dumbbell bond length distribution and inclination angle distribution as well as the effects of element Zr and Y in the compounds, are found to be in agreement with physical analysis and experiment.

The computational evolution from ordered SmCo 5 (CaCu 5 -type) compound to disordered SmCo 7 (TbCu 7 -type) compound has been implemented in this work. Based on statistical simulation, both the phase stabilities and the lattice constants of the calculated SmCo 7 series are in good agreement with experiments and a sort of 3g layer twisting deformation is observed. The calculated site preferences and lattice constants of the disordered ternary SmCo 7− x T x (T = Ti, Ga, Si, Cu, Hf, Zr) are also in consonance with experimental data. SmCo 7 's natural structure selection has also been investigated and understood on the basis of phase stability and cohesive energy. This work lays a foundation for further first principles studies on the magnetic properties of disordered TbCu 7 -type high-temperature permanent magnets.

We report highly efficient and stable organic light-emitting diodes (OLEDs) with MoO3-doped perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) as hole injection layer (HIL). A green OLED with structure of ITO/20 wt% MoO3: PTCDA/NPB/Alq(3)/LiF/Al shows a long lifetime of 1012 h at the initial luminance of 2000 cd/m(2), which is 1.3 times more stable than that of the device with MoO3 as HIL. The current efficiency of 4.7 cd/A and power efficiency of 3.7 lm/W at about 100 cd/m(2) have been obtained. The charge transfer complex between PTCDA and MoO3 plays a decisive role in improving the performance of OLEDs.

The tandem organic light-emitting diodes (OLEDs) with an effective charge-generation connection structure of Mg-doped tris(8-hydroxyquinoline) aluminum (Alq(3))/Molybdenum oxide (MoO3)-doped 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) were presented. At a current density of 50 mA/cm(2), the current efficiency of the tandem OLED with two standard NPB/Alq(3) emitting units is 4.2 cd/A, which is 1.7 times greater than that of the single EL device. The tandem OLED with the similar connection structure of Mg-doped PTCDA/MoO3-doped PTCDA was also fabricated and the influences of the different connection units on the current efficiency of the tandem OLED were discussed as well.

A wide variety of activation ions have been used as near infrared (NIR) luminescent centres. However, when it comes to persistent luminescence, the numbers of known activators are relatively low. Here, we propose a holistic design concept for NIR long persistent phosphors, and successfully fabricate a series of novel Mn4+-doped MAlO3 (M = La, Gd) persistent phosphors with the emission maximum around 730 nm. By drilling down into the details of defect types and trap depths, an improvement of persistent time over 20 h is realized by co-doping Ge4+/Mn4+. The obtained imaging of deep tissues reveals that the new luminescent indicators will open the possibility of advanced optical imaging, with high resolution and weak light disturbance, for factual assessment of the structural and functional processes in cells, tissue and other complex systems.

A phosphor with remarkable long persistent luminescence features, Zn3Ga2Sn1O8:0.5 Cr3+, suitable for deep and reproducible tissue imaging has been rationally designed and successfully fabricated. This phosphor shows bright and long persistent luminescence over 300 h in the near-infrared region, and permits an enabling long-term, reproducible, real-time and reliable structural imaging of deep tissues. Moreover, the revived luminescence and persistent luminescence under the excitation of near-infrared incoherent light are also demonstrated to reveal an optional multiplexed detection. This new luminescent indicator will allow repeatable visualization of the structural and functional processes in cells, tissues and other complex systems. In addition, multifarious and systematic investigations are successfully carried out to unravel the nature of traps and also to verify the rationality of the material design.

Ultrathin Al combined with a buffer layer of MoO3 doped perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) has been demonstrated as an efficient semitransparent anode in OLED. The ITO-free OLED utilizing this composite anode exhibits a low turn on voltage of 2.6 V and a high current efficiency of 5.6 cd A−1. Based on accelerated degradation tests, a device half-life of about 945 h was obtained at an initial device luminance of 100 cd m−2. The charge transfer (CT) complexes formed between MoO3 and PTCDA played a critical role in promoting hole injection. The buffer layer also kept a smooth and thermal stable morphology, which benefits the stability of OLED greatly.

In this article, we explored in detail the influences of organic–inorganic interfacial properties on the performance of a hybrid near-infrared optical upconverter, mainly the leakage current and brightness. The upconverter that can convert input near-infrared to visible light was fabricated by directly integrating an organic light emitting diode (OLED) with an In0.12Ga0.88As/GaAs multi-quantum wells (MQWs) photodetector (PD). MoO3 doped perylene-3,4,9,10-tetra carboxylic dianhydride (PTCDA) was inserted between the PD and OLED as an interfacial connection layer. The possible interaction mechanism of the PTCDA molecule on the GaAs surface such as π electron cloud spreading or Ga–O–C bonds model was suggested and verified to explain the excellent hole injection property at the GaAs/MoO3:PTCDA interface. In addition, choosing an effective interface passivation layer was proven to retain leakage current markedly.