Preparation of Waterproof Organometal Halide Perovskite Photonic Crystal Beads

Herein, we report on an innovative method for the preparation of a series of organometal halide perovskite (OHP) photonic crystal beads with pronounced and tunable photonic stop bands by using self-assembled polystyrene spheres as a mold. After infiltration of the mold with OHP precursor solution and slow drying, the OHPs crystallized in the voids of the polystyrene arrays. By controlling the diameter of the polystyrene spheres, the photonic stop band of the OHPs could be precisely tuned. The overlap between the photonic stop band of the beads and the band gap of the OHPs enhances the light harvesting of the perovskite because of the slow photon effect, which arises from the photonic crystal beads. Moreover, the stability of the composite was greatly enhanced by coating with the transparent polymer PDMS without blocking the light propagation. The coated OHP photonic beads kept their composition even after having been in contact with water for 24 h.     

Organic Cocrystals: Beyond Electrical Conductivities and Field‐Effect Transistors (FETs)

Organic cocrystals based on noncovalent intermolecular interactions (weak interactions) have aroused interest owing to their unpredicted and versatile chemicophysical properties and their applications. In this Minireview, we highlight recent research on organic cocrystals on reducing the aggregation‐caused quenching (ACQ) effect, tuning light emission, ferroelectricity and multiferroics, optical waveguides, and stimuli‐responsiveness. We also summarize the progress made in this field including revealing the structure–property relationships and developing unusual properties. Moreover, we provide a discussion on current achievements, limitations and perspectives as well as some directions and inspiration for further investigation on organic cocrystals.     

Cove‐Edge Nanoribbon Materials for Efficient Inverted Halide Perovskite Solar Cells

Two cove‐edge graphene nanoribbons hPDI2‐Pyr‐hPDI2 ( 1 ) and hPDI3‐Pyr‐hPDI3 ( 2 ) are used as efficient electron‐transporting materials (ETMs) in inverted planar perovskite solar cells (PSCs). Devices based on the new graphene nanoribbons exhibit maximum power‐conversion efficiencies (PCEs) of 15.6 % and 16.5 % for 1 and 2 , respectively, while a maximum PCE of 14.9 % is achieved with devices based on [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM). The interfacial effects induced by these new materials are studied using photoluminescence (PL), and we find that 1 and 2 act as efficient electron‐extraction materials. Additionally, compared with PC₆₁BM, these new materials are more hydrophobic and have slightly higher LUMO energy levels, thus providing better device performance and higher device stability.     

Ethanol‐Precipitable,Silica‐Passivated Perovskite Nanocrystals Incorporated into Polystyrene Microspheres for Long‐Term Storage and Reusage

Perovskite nanocrystals (PNCs) are emerging luminescent materials due to their fascinating physic‐optical properties. However, their sensitive surface chemistry with organic polar solvents, oxygen, and moisture greatly hinders their developments towards practical applications. Herein we promote silica‐passivated PNCs (SP‐PNCs) by in situ hydrolyzing the surface ligands of (3‐aminopropyl) triethoxysilane. The resultant SP‐PNCs possesses a high quantum yield (QY) of 80 % and are precipitable by polar solvents, such as ethanol and acetone, without destroying their surface chemistry or losing QY, which offers an eco‐friendly and efficient method for separation, purification, and phase transfer of PNCs. Moreover, we further promoted a swelling–deswelling encapsulation process to incorporate the as‐made SP‐PNCs into non‐crosslinked polystyrene microspheres (PMs), which can largely increase the stability of the SP‐PNCs against moisture for long‐term storage.     

Size‐ and Halide‐Dependent Auger Recombination in Lead Halide Perovskite Nanocrystals

Lead halide perovskite nanocrystals (NCs) hold strong promise for a variety of light‐harvesting, emitting, and detecting applications, all of which, however, could be complicated by multicarrier Auger recombination. Therefore, complete documentation of the size‐ and composition‐dependent Auger recombination rates of these NCs is highly desirable, as it can guide system design in many applications. Herein we report the synthesis and Auger measurements of monodisperse APbX₃ (A=Cs and FA; X=Cl, Br, and I) NCs in an extensive size range (ca. 3–9 nm). The biexciton Auger lifetime of all the NCs scales linearly with the NC volume. The scaling coefficient is virtually independent of the cation but rather depends sensitively on the anion, and is 0.035, 0.085, and 0.142 ps nm^?3 for Cl, Br, and I, respectively. In all of these nanocrystals the Auger recombination is much faster than in standard CdSe and PbSe NCs (ca. 1 ps nm^?3).     

Protecting‐Group‐Controlled Enzymatic Glycosylation of Oligo‐N‐Acetyllactosamine Derivatives

We describe a chemoenzymatic strategy that can give a library of differentially fucosylated and sialylated oligosaccharides starting from a single chemically synthesized tri‐N‐acetyllactosamine derivative. The common precursor could easily be converted into 6 different hexasaccharides in which the glucosamine moieties are either acetylated (GlcNAc) or modified as a free amine (GlcNH₂) or Boc (GlcNHBoc). Fucosylation of the resulting compounds by a recombinant fucosyl transferase resulted in only modification of the natural GlcNAc moieties, providing access to 6 selectively mono‐ and bis‐fucosylated oligosaccharides. Conversion of the GlcNH₂ or GlcNHBoc moieties into the natural GlcNAc, followed by sialylation by sialyl transferases gave 12 differently fucosylated and sialylated compounds. The oligosaccharides were printed as a microarray that was probed by several glycan‐binding proteins, demonstrating that complex patterns of fucosylation can modulate glycan recognition.     

Composition‐Dependent Hot Carrier Relaxation Dynamics in Cesium Lead Halide (CsPbX3, X=Br and I) Perovskite Nanocrystals

Cesium‐based perovskite nanocrystals (NCs) have outstanding photophysical properties improving the performances of lighting devices. Fundamental studies on excitonic properties and hot‐carrier dynamics in perovskite NCs further suggest that these materials show higher efficiencies compared to the bulk form of perovskites. However, the relaxation rates and pathways of hot‐carriers are still being elucidated. By using ultrafast transient spectroscopy and calculating electronic band structures, we investigated the dependence of halide in Cs‐based perovskite (CsPbX₃ with X=Br, I, or their mixtures) NCs on the hot‐carrier relaxation processes. All samples exhibit ultrafast (<0.6 ps) hot‐carrier relaxation dynamics with following order: CsPbBr₃ (310 fs)>CsPbBr_1.5I_1.5 (380 fs)>CsPbI₃ NC (580 fs). These result accounts for a reduced light emission efficiency of CsPbI₃ NC compared to CsPbBr₃ NC.     

Morphology‐Controlled Synthesis of Organometal Halide Perovskite Inverse Opals

The booming development of organometal halide perovskites in recent years has prompted the exploration of morphology‐control strategies to improve their performance in photovoltaic, photonic, and optoelectronic applications. However, the preparation of organometal halide perovskites with high hierarchical architecture is still highly challenging and a general morphology‐control method for various organometal halide perovskites has not been achieved. A mild and scalable method to prepare organometal halide perovskites in inverse opal morphology is presented that uses a polystyrene‐based artificial opal as hard template. Our method is flexible and compatible with different halides and organic ammonium compositions. Thus, the perovskite inverse opal maintains the advantage of straightforward structure and band gap engineering. Furthermore, optoelectronic investigations reveal that morphology exerted influence on the conducting nature of organometal halide perovskites.     

Ligand‐Controlled Regiodivergent and Enantioselective Copper‐Catalyzed Hydroallylation of Alkynes

A ligand‐controlled regiodivergent and enantioselective copper‐catalyzed intermolecular hydroallylation of alkynes with allylic phosphates and hydrosilanes has been achieved for the first time. The chiral bidentate sulfonate‐containing N‐heterocyclic carbene ligated CuCl complex leads to enantioenriched S_N2′‐type products, whereas the use of the IMesCuCl catalyst affords S_N2‐type products. Thus a range of chiral branched and achiral linear 1,4‐dienes could be facilely synthesized from readily available alkynes in a regiodivergent manner.     

Kinetically Controlled Layer‐by‐Layer Stacking of Metal Oxide 2D Nanosheets

An efficient chemical way to finely control the layer‐by‐layer stacking of inorganic nanosheets (NS) is developed by tuning the type and composition of intercalant ion, and the reaction temperature for restacking process. The finely controlled stacking of NS relies on a kinetic control of the self‐assembly of NS in the presence of coordinating organic cations. A critical role of organic cations in this assembly highlights the importance of the appropriate activation energy. Of prime importance is that a fine‐control of the interstratification of 2D NS is highly effective not only in tailoring its pore structure but also in enhancing its electrode activity. The present study clearly demonstrates that the kinetically controlled restacking of NS provides a facile and powerful method to tailor their stacking number and functionality.     

Lewis Acid–Base Interaction‐Controlled ortho‐Selective C−H Borylation of Aryl Sulfides

An iridium/bipyridine‐catalyzed ortho ‐selective C−H borylation of aryl sulfides was developed. High ortho ‐selectivity was achieved by a Lewis acid–base interaction between a boryl group of the ligand and a sulfur atom of the substrate. This is the first example of a catalytic and regioselective C−H transformation controlled by a Lewis acid–base interaction between a ligand and a substrate. The C−H borylation reaction could be conducted on a gram scale, and with a bioactive molecule as a substrate, demonstrating its applicability to late‐stage regioselective C−H borylation. A bioactive molecule was synthesized from an ortho ‐borylated product by converting the boryl and methylthio groups of the product.     

Heteroepitaxial Growth of Multiblock Ln‐MOF Microrods for Photonic Barcodes

Micro/nanoscale multicolor barcodes with unique identifiability and a small footprint play significant roles in applications such as multiplexed labeling and tracking systems. Now, a strategy is reported to design multicolor photonic barcodes based on 1D Ln‐MOF multiblock heterostructures, where the domain‐controlled emissive colors and different block lengths constitute the fingerprint of a corresponding heterostructure. The excellent heteroepitaxial growth characteristics of MOFs enable the effective modulation of the coding structures, thereby remarkably increasing the encoding capacity. The as‐prepared multicolor barcodes enable an efficient authentication and exhibit great potential in fulfilling the functions of anti‐counterfeiting, information security, and so on. The results will pave an avenue to novel hybrid MOFs for optical data recording and security labels.