Chemical transformation mechanism for blue-to-green emitting CsPbBr3 nanocrystals.

Recently, metal-halide perovskites have rapidly emerged as efficient light emitters with near-unity quantum yield and size-dependent optical and electronic properties, which have attracted considerable attention from researchers. However, the ultrafast nucleation rate of ionic perovskite counterparts severely limits the in-depth exploration of the growth mechanism of colloidal nanocrystals (NCs). Herein, we used an inorganic ligand nitrosonium tetrafluoroborate (NOBF4) to trigger a slow post-synthesis transformation process, converting non-luminescent Cs4PbBr6 NCs into bright green luminescent CsPbBr3 NCs to elucidate the concrete transformation mechanism via four stages: (i) the dissociation of pristine NCs, (ii) the formation of Pb-Br intermediates, (iii) low-dimensional nanoplatelets (NPLs) and (iv) cubic CsPbBr3 NCs, corresponding to the blue-to-green emission process. The desorption and reorganization of organic ligands induced by NO+ and the involvement of BF4- in the ligand exchange process played pivotal roles in this dissolution-recrystallization of NCs. Moreover, controlled shape evolution from anisotropic NPLs to NCs was investigated through variations in the amount of NOBF4. This further validates that additives exert a decisive role in the symmetry and growth of nanostructured perovskite crystals during phase transition based on the ligand-exchange mechanism. This finding serves as a source of inspiration for the synthesis of highly luminescent CsPbBr3 NCs, providing valuable insights into the chemical mechanism in post-synthesis transformation.

Ligands in Lead Halide Perovskite Nanocrystals: From Synthesis to Optoelectronic Applications.

Ligands are indispensable for perovskite nanocrystals (NCs) throughout the whole lifetime, as they not only play key roles in the controllable synthesis of NCs with different sizes and shapes, but also act as capping shell that affects optical properties and electrical coupling of NCs. Establishing a systematic understanding of the relationship between ligands and perovskite NCs is significant to enable many potential applications of NCs. This review mainly focuses on the influence of ligands on perovskite NCs. First of all, the ligands-dominated size and shape control of NCs is discussed. Whereafter, the surface defects of NCs and the bonding between ligands and perovskite NCs are classified, and corresponding post-treatment of surface defects via ligands is also summarized. Furthermore, advances in engineering the ligands towards the high performance of optoelectronic devices based on perovskite NCs, including photodetector, solar cell, light emitting diode (LED), and laser, and finally to potential challenges are also discussed.

Identification and Characterization of Auxin/IAA Biosynthesis Pathway in the Rice Blast Fungus Magnaporthe oryzae.

The rice blast fungus Magnaporthe oryzae has been known to produce the phytohormone auxin/IAA from its hyphae and conidia, but the detailed biological function and biosynthesis pathway is largely unknown. By sequence homology, we identified a complete indole-3-pyruvic acid (IPA)-based IAA biosynthesis pathway in M. oryzae, consisting of the tryptophan aminotransferase (MoTam1) and the indole-3-pyruvate decarboxylase (MoIpd1). In comparison to the wild type, IAA production was significantly reduced in the motam1Δ mutant, and further reduced in the moipd1Δ mutant. Correspondingly, mycelial growth, conidiation, and pathogenicity were defective in the motam1Δ and the moipd1Δ mutants to various degrees. Targeted metabolomics analysis further confirmed the presence of a functional IPA pathway, catalyzed by MoIpd1, which contributes to IAA/auxin production in M. oryzae. Furthermore, the well-established IAA biosynthesis inhibitor, yucasin, suppressed mycelial growth, conidiation, and pathogenicity in M. oryzae. Overall, this study identified an IPA-dependent IAA synthesis pathway crucial for M. oryzae mycelial growth and pathogenic development.

High Performance Quasi-2D Perovskite Sky-Blue Light-Emitting Diodes Using a Dual-Ligand Strategy.

For quasi-2D perovskite light-emitting diodes, the introduction of insulating bulky cation reduces the charge transport property, leading to lowered brightness and increased turn-on voltage. Herein, a dual-ligand strategy is adopted to prepare perovskite films by using an appropriate ratio of i-butylammonium (iBA) and phenylethylammonium (PEA) as capping ligands. The introduction of iBA enhances the binding energy of the ligands on the surface of the quasi-2D perovskite, and effectively controls the proportion of 2D perovskite to allow more efficient energy transfer, resulting in the great enhancement of the electric and luminescent properties of the perovskite. The photoluminescence (PL) mapping of the perovskite films exhibits that enhanced photoluminescence performance with better uniformity and stronger intensity can be achieved with this dual-ligand strategy. By adjusting the proportion of the two ligands, sky-blue perovskite light-emitting diodes (PeLEDs) with electroluminescence (EL) peak located 485 nm are achieved with a maximum luminance up to 1130 cd m-2 and a maximum external quantum efficiency (EQE) up to 7.84%. In addition, the color stability and device stability are significantly enhanced by using a dual-ligand strategy. This simple and feasible method paves the way for improving the performance of quasi-2D PeLEDs.

MoGT2 Is Essential for Morphogenesis and Pathogenicity of Magnaporthe oryzae.

Magnaporthe oryzae causes the rice blast disease, which is one of the most serious diseases of cultivated rice worldwide. Glycosylation is an important posttranslational modification of secretory and membrane proteins in all eukaryotes, catalyzed by glycosyltransferases (GTs). In this study, we identified and characterized a type 2 glycosyltransferase, MoGt2, in M. oryzae Targeted gene deletion mutants of MoGT2 (mogt2Δ strains) were nonpathogenic and were impaired in vegetative growth, conidiation, and appressorium formation at hyphal tips. Moreover, MoGT2 plays an important role in stress tolerance and hydrophobin function of M. oryzae Site-directed mutagenesis analysis showed that conserved glycosyltransferase domains (DxD and QxxRW) are critical for biological functions of MoGt2. MoGT2 deletion led to altered glycoproteins during M. oryzae conidiation. By liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified several candidate proteins as potential substrates of MoGt2, including several heat shock proteins, two coiled-coil domain-containing proteins, aminopeptidase 2, and nuclease domain-containing protein 1. On the other hand, we found that a conidiation-related gene, genes involved in various metabolism pathways, and genes involved in cell wall integrity and/or osmotic response were differentially regulated in the mogt2Δ mutant, which may potentially contribute to its condiation defects. Taken together, our results show that MoGt2 is important for infection-related morphogenesis and pathogenesis in M. oryzaeIMPORTANCE The ascomycete fungus Magnapothe oryzae is the causal agent of rice blast disease, leading to severe loss in cultivated rice production worldwide. In this study, we identified a conserved type 2 glycosyltransferase named MoGt2 in M. oryzae The mogt2Δ targeted gene deletion mutants exhibited pleiotropic defects in vegetative growth, conidiation, stress response, hyphal appressorium-mediated penetration, and pathogenicity. Furthermore, conserved glycosyltransferase domains are critical for MoGt2 function. The comparative transcriptome analysis revealed potential target genes under MoGt2 regulation in M. oryzae conidiation. Identification of potential glycoproteins modified by MoGt2 provided information on its regulatory mechanism of gene expression and biological functions. Overall, our study represents the first report of type 2 glycosyltransferase function in M. oryzae infection-related morphogenesis and pathogenesis.

Achieving Balanced Charge Injection of Blue Quantum Dot Light-Emitting Diodes through Transport Layer Doping Strategies.

For blue quantum dot (QD) light-emitting diodes (QLEDs), the imbalance of charges transport and injection severely affects their efficiency and lifetime. A better charge balance can be realized by improving hole injection while suppressing redundant electrons. Introducing dopants into charge transport layers (CTLs) is an effective and simple strategy to modulate the charge injection barrier and mobility. In this work, optoelectronic simulation is performed to investigate the change in physical process within the devices upon CTL doping. The results confirm that the charge distribution in the QD layer is more balanced and the recombination rate is greatly improved. Under the guidance of theoretical simulation, high-performance blue QLEDs were achieved by fine-tuning the charge balance through CTL doping. The luminance and external quantum efficiency have been dramatically increased from 18 679 to 34 874 cd/m2 and from 4.7 to 10.7%, respectively. The operation lifetime is also improved ∼3.5 times due to the more balanced charge injection.

All-solution-processed perovskite light-emitting diodes with all metal oxide transport layers.

All-solution-processed perovskite light-emitting diodes (PeLEDs) with all metal oxide transport layers were successfully realized based on an ITO/NiOx/CsPbBr3/ZnMgO/Al conventional device structure. A unique perovskite-polymer composite method enables the deposition of solution-processed ZnMgO nanoparticles on the perovskite film. As a result, we achieved highly efficient PeLEDs with a maximum luminance of 17 017 cd m-2, and the efficiency showed little roll-off with increasing current density.