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81.
Improving the Stability and Performance of Perovskite Light‐Emitting Diodes by Thermal Annealing Treatment
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82.
The crystal structure, electronic and optical properties of double perovskite Sr2MgMoO6 have been calculated by using the full-potential linear augmented plane wave (FP-LAPW) method. The band structure and density of states (DOS) were carried out by the modified Becke–Johnson (mBJ) exchange potential approximation based on the density functional theory (DFT). The calculated band structure shows a direct band gap (Γ–Γ) of 2.663 eV for Sr2MgMoO6. The compound Sr2MgMoO6 has a triclinic structure with the space group I-1, the lattice parameters a=5.5666 Å, b=5.5661 Å and c=7.9191 Å, which are used in our calculations. The optical parameters, like dielectric constant, refractive index, reflectivity and energy loss function were also calculated and analyzed. This work provides the first quantitative theoretical prediction of the optical properties and electronic structure for the triclinic phase of Sr2MgMoO6. 相似文献
83.
Yanfeng Li Denghui Ji Shaopeng Liu Guide Tang Zhuangzhi Li Yuxi Yao Denglu Hou Minggang Zhu 《稀有金属(英文版)》2012,31(4):379-386
The fact that there are Mn2+ at the A sites in the ABO3 perovskite phase of manganites with the nominal composition La0.6-xNdxSr0.1MnO3 showed by detailed experimental study and theoretical calculations.The magnetic moments of these Mn2+ are antiparallel to those of the Mn ions at the B sites.The content of the Mn2+ increases as the average ionic radius,(rA),of the ions at A sites decreases,resulting in the experimentally observed phenomenon that the content of the Mn3O4 phase in the manganites decreases with decreasing 〈rA〉. 相似文献
84.
The aim of this work was to investigate the performance and stability of the perovskite La0.5Sr0.5CoO3−δ, as a potential catalyst precursor, for the synthesis gas production by partial oxidation of methane. For this purpose, the catalytic activity of La0.5Sr0.5CoO3−δ was studied as a function of the temperature, flow rate and feed composition. In addition, its stability with the time-on-stream and redox cycles was also explored. Before and after testing, the catalyst precursor was characterized by X-ray diffraction, SEM-EDX and specific surface area (BET). The results evidenced a remarkable catalytic activity due to the stability of the cobalt, which is in a highly disperse state, in its reduced state. The CH4 conversion and the CO and H2 selectivities were enhanced with the increase of redox cycles. Finally, the precursor was totally regenerated to the initial perovskite structure under a specific thermal treatment. 相似文献
85.
Molecular design of interfacial layers based on conjugated polythiophenes for polymer and hybrid solar cells
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Judith E Houston Sébastien Richeter Sébastien Clément Rachel C Evans 《Polymer International》2017,66(10):1333-1348
In the past two decades, bulk heterojunction organic photovoltaic (OPV) devices have emerged as attractive candidates for solar energy conversion due to their lightweight design and potential for low‐cost, high‐throughput, solution‐phase processability. Interfacial engineering is a proven efficient approach to achieve OPV devices with high power conversion efficiencies. This mini‐review provides an overview of the key structural considerations necessary when undertaking the molecular design of conjugated polyelectrolytes, for application as interfacial layers (ILs). The different roles of ILs are outlined, together with the advantages and disadvantages of competing classes of IL materials. Particular emphasis is placed on the design and synthesis of water‐soluble polythiophene‐based IL materials and the influence of their structural characteristics on their performance as a promising class of IL material. Finally, the challenges and opportunities for polythiophenes as IL materials for OPV devices and other solution‐processed solar cell technologies (e.g. perovskite solar cells) are discussed. © 2017 Society of Chemical Industry 相似文献
86.
This review underlines the importance of the developments in perovskite catalysts for methane combustion from the past up to the present. In this review, after a general and brief introduction to perovskites, the mechanisms of catalytic combustion of methane have been included. Moreover, current studies on perovskites have been summarized including the effects of substitutions, doped perovskites, perovskite preparation methods, and the effect of sulfur presence on perovskite catalysts. Besides, recent studies on perovskite oxides and phenomenon of oxygen (O2) deficiency, porous perovskite oxides, and nanostructured perovskites have been conducted. In addition, partial oxidation of methane (POM) has been reviewed. The loss of active component during the POM reaction can take place in the nickel catalyst, in particular. Since nickel has a lower melting point than noble metals and other active components, such as Co and Fe, in general, to deactivate nickel is easier. Compared with conventional structure, the porous structure with the unique morphology significantly enhances the catalytic activity through a much larger surface area (SA) and greater reactivity of the active sites. Furthermore, the monolithic nanoarrayed perovskite presents very good results in well‐defined faceted catalysts and takes part in porous channel hydrocarbon combustion. This review study is prepared as a guide to cover the profound knowledge of perovskite oxides catalysts, considering the methane combustion reaction mechanisms, and addresses prospective studies in this field for researchers. 相似文献
87.
Due to the excellent optoelectronic properties, organic–inorganic perovskites have drawn much attention and have been applied in different electronics with remarkable performance. However, the poor stability creates a massive barrier for the commercialization of perovskite electronic devices. In this review, we discuss intrinsic and extrinsic factors causing instabilities of perovskites and perovskite devices such as solar cells, liquid crystal displays (LCDs), light emitting diodes (LEDs), ionizing radiation detectors, transistors, memristors and sensors. We further review the stabilization approaches, including composition engineering, adoption of lower dimensional compositions, quantum dots, interface engineering, defects engineering and so on. 相似文献
88.
Changbai Long Huiqing Fan Wei Ren Jinyan Zhao 《Journal of the European Ceramic Society》2019,39(14):4103-4112
This work reports the existence of double polarization hysteresis (P–E) loop in Aurivillius-phase ferroelectric Bi4Ti3O12 (BiT) and reveals dramatic influence of small compositional variations on the electrical properties of it. The double polarization hysteresis is a characteristic of the interaction of defects with domain walls. This characteristic becomes more pronounced in Bi-deficient and Mg-doped BiT due to an increase in oxygen vacancy concentration at the lattices. Normal and saturated P–E loop is recalled by Nb donor doping, and associated composition Bi4Ti2.97Nb0.03O12.015 (BiT-0.03Nb) shows high remnant polarization (Pr = 12.5 μC/cm2) and large field-induced strain (S33 = 5.6 × 10?4). In addition, this doping results in bulk conductivity (σb) of BiT decreasing dramatically and associated activity energy (Ea) increasing significantly. In contrast, high oxide ion conductivity is induced with Mg2+ acceptor doping, and at 600 °C the optimum composition has ionic conductivity of ?0.65 × 10?2 S cm?1 in the bulk. 相似文献
89.
《Ceramics International》2022,48(2):1765-1770
Perovskite lattice was tailored by introducing site vacancies and mixed anion composition, to produce Sr0.83Li0.17Ta0.83O1.88N0.74 (Li02N). Further, Li02N was converted to a defect oxide Sr0.83Li0.17Ta0.83O3 (Li02O) by applying an optimized treatment: heating in air at 1173 K for 2 h. According to the neutron Rietveld refinement, Li02N and Li02O are tetragonal and orthorhombic, respectively, where the lattice volume of Li02O is significantly smaller than that of Li02N. The ionic conductivity (σion) of Li02N and Li02O was evaluated by the ac impedance spectroscopy and the equivalent circuit analysis. Both Li02N (σion = 10?5.5 S/cm at 671 K) and Li02O (σion = 10?6.2 S/cm at 667 K) exhibited an Arrhenius behavior of ionic conductivity with activation energies of 0.87 eV and 0.75 eV, respectively. It is interpreted that the nitride component enhances the ionic conduction of Li02N, while the vacancy of the anion lattice makes an opposite effect. 相似文献
90.
An efficient red phosphorescent organic light emitting diode (PhOLED) has been realized by utilizing a composite hole transporting layer comprised of all-inorganic cesium lead halide perovskite CsPbBr3 via spin-coating and 1,3-bis(9-carbazolyl) benzene (mCP) by vacuum depositing, in which CsPbBr3 film is used as a hole transporting layer and mCP plays a dominant role in electron and exciton blocking. And this PhOLED shows a saturated red emission coordinated at CIE (0.65, 0.33) driven at 7.5 V, a maximum brightness of 20,750 cd/m2, and a maximum current efficiency of 10.64 cd/A, which is as 1.87 times as that 5.68 cd/A of the reference PhOLEDs based on traditional small organic molecular hole transporting material N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzi (NPB). The electroluminescent (EL) spectra and the energy level alignment of different PhOLEDs are investigated. The enhanced EL performances are ascribed to improved hole injecting and transporting behaviors, and better electron and exciton confinements by introducing the composite hole transporting layer CsPbBr3/mCP. 相似文献