Ions-induced Epitaxial Growth of Perovskite Nanocomposites for Highly Efficient Light-Emitting Diodes with EQE Exceeding 30%

Cesium lead bromide (CsPbBr3) is a widely used emitter for perovskite light-emitting diodes (PeLEDs), benefiting from its large carrier mobility, high color purity and good thermal stability. However, the three-dimensional CsPbBr3 films encounter challenges due to their massive intrinsic defects and weak exciton binding effect, which limited their electroluminescence efficiency. To address this issue, the prevailing approach is to confine carriers by reducing dimensionality or size. Nonetheless, this method results in an increase in surface trap states due to the larger surface-to-volume ratio and presents difficulties in carrier injection and transport after reducing lattice splitting to smaller sizes. Here, we successfully achieved proper control over film crystallization by introducing sodium ions, which facilitate the epitaxial growth of zero-dimensional Cs4PbBr6 on the surface of CsPbBr3, forming large grain matrixes where CsPbBr3 is encapsulated by Cs4PbBr6. Notably, the ions-induced epitaxial growth enables the CsPbBr3 emitter with significantly reduced trap states, and generates coarsened nanocomposites of CsPbBr3&Cs4PbBr6 with grain size that surpass the average thickness of the thin perovskite film, resulting in a wavy surface conducive to light out-coupling. Additionally, another additive of formamidinium chloride was incorporated to assist the growth of nanocomposites with larger size and lower defects as well as better carrier injection and transportation. As a result, our demonstrated PeLEDs based on the coarsened nanocomposites exhibit low nonradiative recombination, enhanced light extraction and well-balanced carrier transportation, leading to high-performance devices. The champion device achieved an external quantum efficiency of 31.0% at the emission peak of 521 nm with a narrow full width at half-maximum (FWHM) of 18 nm

Ti–6Al–4V alloy prepared by laser powder bed fusion of a coarse powder

ABSTRACTA Ti–6Al–4V (wt%) alloy was prepared by laser powder bed fusion (LPBF) of a coarse powder with particle sizes in the range of 50–200 μm. The effect of volume energy density (VED) on cavities/pores, microstructure and mechanical properties of the LPBF-fabricated samples was investigated. The results showed that with the increase of VED, the content of cavities/pores decreased. When the VED was 100 J/mm3 and above, the content of cavities/pores decreased to below 0.3%, and the yield strength (YS), ultimate tensile strength (UTS) and elongation to fracture reached 1032, 1052 MPa and 7.0%, which are close to the tensile properties of Ti–6Al–4V alloy prepared by LPBF of a fine powder (particle sizes: 15–53 μm). The microstructure of the samples consisted of β-columnar crystals containing acicular α′ martensite. After vacuum annealing at 800°C and 900°C respectively, the microstructure of the fabricated samples changed to an α+β lamellar structure, with a substantial decrease in YS and UTS to 836 and 919 MPa, respectively, but a significant increase in elongation to fracture to 15.9%, resulting in very good overall tensile properties. This study shows that with a sufficient VED and proper heat treatment, a Ti–6Al–4V alloy with good metallurgical quality and excellent overall tensile properties can be fabricated by LPBF of a coarse powder

Business Process Complexity Measurement: A Systematic Literature Review

Business process complexity is an important factor that affects process quality and has a significant impact on the maintenance, optimization, and execution efficiency of processes. To review the application progress and trends of process complexity measurement in business process management, this study uses the systematic literature review (SLR) method to qualitatively and quantitatively analyze the theoretical background, rationality, effectiveness, and comprehensiveness of 92 process complexity metrics. The findings showed that the measurement of process complexity primarily encompasses four dimensions: activity complexity, control-flow complexity, data-flow complexity, and resource complexity. However, most metrics consider only one or two aspects of complexity in the process and rely mainly on empirical validation, thus lacking theoretical validation support. Currently, the most popular and widely used complexity metric is Control Flow Complexity (CFC). Process complexity metrics mainly focus on measuring the complexity of process models, and the majority of them focus on activity complexity or control-flow complexity. The future research trend is to combine data mining techniques with process log data to analyze process complexity

Genesis of the Weibao banded skarn Pb-Zn deposit, Qimantagh, Xinjiang: Insights from skarn mineralogy and muscovite Ar-40-Ar-39 dating

The Weibao Pb-Zn deposit is located in the Qimantagh area, Xinjiang (NW China). At Weibao, stratiform Pb-Zn ore bodies are hosted by the skarn-altered Mesoproterozoic Langyashan Formation. Both of the skarn rocks and Pb-Zn ores are banded. The skarn bands are normally 0.5 to 5 cm wide and comprise alternating garnet and pyroxene zones. Systematic mineralogical studies indicate that the Weibao banded skarn was formed by infiltrative metasomatism of magmatic fluids in a disequilibriated geochemical system, rather than by the bimetasomatism between marble and Si-Al units or the metamorphism of calc-silicate-rich submarine exhalative beds. This infiltrative metasomatic process can be further divided into four stages, namely the prograde skarn, retrograde skam, sulfide and carbonate stage. Three garnet types (Garnet I, II and III) and two pyroxene types (Pyroxene I and II) have been identified at Weibao. Garnet I has commonly Fe-rich core and Al-rich rim (Ad(34)Gr(65) to Ad(96)Gr(3)), while Garnet II has a wider composition range (Ad(23)Gr(73) to Ad(97)Gr(2); average: Ad(59)Gr(41)). Garnet III is compositionally more homogeneous and Mn-rich (Ad(17)Sp(3)Gr(80) to Ad(55) Sp(6)Gr(39); average: Ad(47)Sp(4)Gr(49)). Pyroxene I is diopside-rich (Hd(2)Jo(1)Di(79) to Hd(36)Jo(2)Di(62); average Hd(29)Jo(l)Di(70)), while Pyroxene II has lower diopside component (Hd(34)Jo(3)Di(63) to Hd(55)Jo(13)Di(32); average: Hd(48)Jo(5)Di(47)). Garnet I and Pyroxene I may have formed by a small volume of high-temperature and volatile-rich fluids exsolved from the magmas at its initial crystallization stage. Further fractionation generated abundant magmatic fluids that reacted with the impure carbonates through infiltrative metasomatism, forming Garnet II and Pyroxene II in the banded skarn. Garnet III occurs as garnet + sphalerite + galena + calcite veinlets crosscutting the early-stage pyroxene and garnet zones, and may have been a product of late hydrothermal superimposition. Sulfide stage is the main ore-forming stage at Weibao. Sulfide minerals in this stage precipitated mainly through replacing anhydrous (e.g., pyroxene) and hydrous (e.g., amphibole) minerals, or as interstitials among early-formed minerals. A minor amount of the sulfides also occurs as sulfide veins. The sulfide precipitation may have been controlled chiefly by physicochemical changes of ore-forming fluids and the characteristics of early-formed skam minerals. Specifically, hydrothermal replacement of skarn minerals has provided the space for sulfide to precipitate and thus controlled their distribution, and further shaped the mineralization into a banded structure. Ar-40-Ar-39 dating of the syn-mineralization muscovite yielded a Late Triassic age (ca. 226 Ma), which was coeval to the massive post-collisional intermediatefelsic granitoids emplacement in the Qimantagh area. Magmatic fluids evolved from these intermediatefelsic granitoids have induced the regional-scale magmatic hydrothermal mineralization, including that at Weibao. (C) 201 7 Elsevier B.V. All rights reserved

Efficient Quasi-2D Perovskite Light-Emitting Diodes Enabled by Regulating Phase Distribution with a Fluorinated Organic Cation

Metal halide perovskites have become a research highlight in the optoelectronic field due to their excellent properties. The perovskite light-emitting diodes (PeLEDs) have achieved great improvement in performance in recent years, and the construction of quasi-2D perovskites by incorporating large-size organic cations is an effective strategy for fabricating efficient PeLEDs. Here, we incorporate the fluorine meta-substituted phenethylammonium bromide (m-FPEABr) into CsPbBr3 to prepare quasi-2D perovskite films for efficient PeLEDs, and study the effect of fluorine substitution on regulating the crystallization kinetics and phase distribution of the quasi-2D perovskites. It is found that m-FPEABr allows the transformation of low-n phases to high-n phases during the annealing process, leading to the suppression of n = 1 phase and increasing higher-n phases with improved crystallinity. The rational phase distribution results in the formation of multiple quantum wells (MQWs) in the m-FPEABr based films. The carrier dynamics study reveals that the resultant MQWs enable rapid energy funneling from low-n phases to emission centers. As a result, the green PeLEDs achieve a peak external quantum efficiency of 16.66% at the luminance of 1279 cd m−2. Our study demonstrates that the fluorinated organic cations would provide a facile and effective approach to developing high-performance PeLEDs

Transcriptional insights of citrus defense response against Diaporthe citri

Abstract Citrus melanose, caused by Diaporthe citri, is one of the most important and widespread fungal diseases of citrus. Previous studies demonstrated that the citrus host was able to trigger the defense response to restrict the spread of D. citri. However, the molecular mechanism underlying this defense response has yet to be elucidated. Here, we used RNA-Seq to explore the gene expression pattern at the early (3 days post infection, dpi) and late (14 dpi) infection stages of citrus leaves in response to D. citri infection, and outlined the differences in transcriptional regulation associated with defense responses. The functional enrichment analysis indicated that the plant cell wall biogenesis was significantly induced at the early infection stage, while the callose deposition response was more active at the late infection stage. CYP83B1 genes of the cytochrome P450 family were extensively induced in the callus deposition-mediated defense response. Remarkably, the gene encoding pectin methylesterase showed the highest upregulation and was only found to be differentially expressed at the late infection stage. Genes involved in the synthesis and regulation of phytoalexin coumarin were effectively activated. F6’H1 and S8H, encoding key enzymes in the biosynthesis of coumarins and their derivatives, were more strongly expressed at the late infection stage than at the early infection stage. Collectively, our study profiled the response pattern of citrus leaves against D. citri infection and provided the transcriptional evidence to support the defense mechanism