Enhancing corannulene chemiluminescence, electrochemiluminescence and photoluminescence by means of an azabora-helicene to slow down its bowl inversion.

Aromatic system extension of corannulene (Cor) is a synthetic challenge to access non-planar polyaromatic hydrocarbons (PAHs). Herein, we report the design and synthesis of azaborahelicene corannulene 1 through hybridization of an azabora[5] helical structure and subsequent luminescence studies. Significant enhancement in chemiluminescence (CL), electroluminescence (ECL) and photoluminescence (PL) is achieved compared to those of pristine Cor.

Stable Interfacial Ruthenium Species for Highly Efficient Polyolefin Upcycling.

The present polyolefin hydrogenolysis recycling cases acknowledge that zerovalent Ru exhibits high catalytic activity. A pivotal rationale behind this assertion lies in the propensity of the majority of Ru species to undergo reduction to zerovalent Ru within the hydrogenolysis milieu. Nonetheless, the suitability of zerovalent Ru as an optimal structural configuration for accommodating multiple elementary reactions remains ambiguous.

Spectroscopy and absolute quantum efficiency of near-infrared electrochemiluminescence for a macrocyclic palladium complex.

Electrochemiluminescence (ECL) is widely applied as a reliable tool in clinical diagnosis, including immunoassays, cancer biomarker detection, etc. Metal complexes with emission in the near-infrared (NIR) range possess distinct features such as high transmission and minimal tissue auto-absorption, making them versatile for applications in biosensing and other fields. Through ECL spectral studies of an O-linked nonaromatic benzitripyrrin (C^N^N^N) macrocyclic palladium complex (Pd1) with multiple pyrrole structures, we observed emission peaks from the Q(0,0) and its vibronic Q(0,1) bands during both photoluminescence (PL) and ECL.

Mitigating the Trade-Off between Non-Radiative Recombination and Charge Transport to Enable Efficient Ternary Organic Solar Cells.

Ternary organic solar cells (OSCs) have attracted intensive studies due to their promising potential for attaining high-performing photovoltaics, whereas there has been an opening challenge in minimizing the open circuit voltage () loss while retaining the optimal carrier extraction in the multiple mixture absorbers. Here, we systemically investigate a ternary absorber comprised of two acceptors and a donor, in which the resultant and fill factor are varied and determined by the ratios of acceptor components as a result of the unbalance of non-radiative recombination rates and charge transport. The transient absorption spectroscopy and electroluminescence techniques verify two distinguishable charge-transfer (CT) states in the ternary absorber, and the mismatch of non-radiative recombination rates of those two CT states is demonstrated to be associated with the deficit, whilst the high-emissive acceptor molecule delivers inferior electron mobility, resulting in poor charge transport and a subpar fill factor.

Integrated Photochromic-Photothermal Processes for Catalytic Plastic Upcycling.

Incorporating high-energy ultraviolet (UV) photons into photothermal catalytic processes may enable photothermal-photochemical synergistic catalysis, which represents a transformative technology for waste plastic recycling. The major challenge is avoiding side reactions and by-products caused by these energetic photons. Here, we break through the limitation of the existing photothermal conversion mechanism and propose a photochromic-photothermal catalytic system based on polyol-ligated TiO nanocrystals.

Local Built-In Field at the Sub-nanometric Heterointerface Mediates Cascade Electrochemical Conversion of Lithium-sulfur Batteries.

Heterogeneous catalytic mediators have been proposed to play a vital role in enhancing the multiorder reaction and nucleation kinetics in multielectron sulfur electrochemistry. However, the predictive design of heterogeneous catalysts is still challenging, owing to the lack of in-depth understanding of interfacial electronic states and electron transfer on cascade reaction in Li-S batteries. Here, a heterogeneous catalytic mediator based on monodispersed titanium carbide sub-nanoclusters embedded in titanium dioxide nanobelts is reported.

Site-Selective Polyolefin Hydrogenolysis on Atomic Ru for Methanation Suppression and Liquid Fuel Production.

Catalytic hydrogenolysis of end-of-life polyolefins can produce value-added liquid fuels and therefore holds great promises in plastic waste reuse and environmental remediation. The major challenge limiting the recycling economic benefit is the severe methanation (usually >20%) induced by terminal C-C cleavage and fragmentation in polyolefin chains. Here, we overcome this challenge by demonstrating that Ru single-atom catalyst can effectively suppress methanation by inhibiting terminal C-C cleavage and preventing chain fragmentation that typically occurs on multi-Ru sites.

Graphene-Like Conjugated Molecule as Hole-Selective Contact for Operationally Stable Inverted Perovskite Solar Cells and Modules.

Further enhancing the operational lifetime of inverted-structure perovskite solar cells (PSCs) is crucial for their commercialization, and the design of hole-selective contacts at the illumination side plays a key role in operational stability. In this work, the self-anchoring benzo[rst]pentaphene (SA-BPP) is developed as a new type of hole-selective contact toward long-term operationally stable inverted PSCs. The SA-BPP molecule with a graphene-like conjugated structure shows a higher photostability and mobility than that of the frequently-used triphenylamine and carbazole-based hole-selective molecules.

High-Efficiency Semitransparent Light-Emitting Diodes with Perovskite Nanocrystals.

Artificial intelligence offers new opportunities for translucent displays. However, achieving translucent light-emitting diodes (LEDs) with high efficiency and high color purity remains a challenge. Here, we propose a strategy of using an alkali metal/inert metal (calcium/silver) bilayer metal electrode as a top electrode and perovskite nanocrystals as an emitter layer in the device structure, which allows us to not only fabricate excellent opaque LEDs but also manufacture highly efficient semitransparent LEDs with high color purity, total brightness (over 7000 cd m), total external quantum efficiency (over 12%), and 56% transmittance around 520 nm.

Analyzing Near-Infrared Electrochemiluminescence of Graphene Quantum Dots in Aqueous Media.

Mechanisms of emissions, especially electrochemiluminescence (ECL), for graphene quantum dots (GQDs) are poorly understood, which makes near-infrared (NIR)-emitting GQDs difficult to create. To explore this poorly understood NIR ECL, two GQDs, nitrogen-doped GQDs (GQD-1) and nitrogen- and sulfur-doped ones (GQD-2), were prepared by a simple one-step solvothermal reaction with similar core structures but different surface states. The GQDs were analyzed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy.

Suppressing Dehydroisomerization Boosts n-Butane Dehydrogenation with High Butadiene Selectivity.

Butadiene (BD) is a critical raw material in chemical industry, which is conventionally produced from naphtha cracking. The fast-growing demand of BD and the limited oil reserve motivate chemists to develop alternative methods for BD production. Shale gas, which mainly consists of light alkanes, has been considered as cheap raw materials to replace oil for BD production via n-butane direct dehydrogenation (n-BDH).

Synthesis of lead halide perovskite nanocrystals by melt crystallization in halide salts.

CsPbBr3 nanocrystals (NCs) are successfully prepared by using SrBr2 salt as a growth medium in a melt crystallization process. The obtained CsPbBr3 NCs exhibit a photoluminescence peak of 524 nm with a narrow emission linewidth of 25 nm, which can offer a wide color gamut display. This study can be extended to other alkali metal and alkali earth metal halides and may become a general method for the synthesis of perovskite NCs.

Metal Halide Perovskite Nanocrystals in Metal-Organic Framework Host: Not Merely Enhanced Stability.

As an emerging optical material, perovskite nanocrystals (NCs) exhibit excellent optoelectronic properties and show great potential for various optoelectronic applications. However, the inherent inferior stability against moisture, oxygen, light and heat limit their practical application. As well, the exploration and development of perovskite NCs with novel properties and functions are new challenges.

High-efficiency perovskite nanocrystal light-emitting diodes via decorating NiO on the nanocrystal surface.

Nickel oxides exhibit a great potential as hole transport layers for the fabrication of efficient perovskite light-emitting diodes (LEDs) due to their high carrier mobility and good energy band matching with perovskite nanocrystals. In this work, nickel oxides were directly decorated on the CsPbBr3 nanocrystal surface through adsorption and a sequential oxidation treatment. The resulting sample shows a high photoluminescence quantum-yield of 82%.

Ceramic-like stable CsPbBr nanocrystals encapsulated in silica derived from molecular sieve templates.

Achieving good stability while maintaining excellent properties is one of the main challenges for enhancing the competitiveness of luminescent perovskite CsPbX (X=Cl, Br, I) nanocrystals (NCs). Here, we propose a facile strategy to synthesize ceramic-like stable and highly luminescent CsPbBr NCs by encapsulating them into silica derived from molecular sieve templates at high temperature (600-900 C). The obtained CsPbBr-SiO powders not only show high photoluminescence quantum yield (~71%), but also show an exceptional stability comparable to the ceramic SrSiO:Eu green phosphor.

Sacrificial oxidation of a self-metal source for the rapid growth of metal oxides on quantum dots towards improving photostability.

Growth of metal oxide layers on quantum dots (QDs) has been regarded as a good way to improve the photostability of QDs. However, direct growth of metal oxides on individual QD remains a great challenge. Here we report a novel approach to rapidly anchor metal oxides on QD surfaces through a sacrificial oxidation of a self-metal source strategy.

Critical role of metal ions in surface engineering toward brightly luminescent and stable cesium lead bromide perovskite quantum dots.

The highly dynamic binding ligands on the surface of all-inorganic cesium lead halide perovskite quantum dots (PQDs), which can be easily lost or detached leading to a deterioration in the optical properties and stability, are one of the greatest challenges for the practical storage and application of PQDs. Herein, we report a facile metal ion-assisted ligand surface engineering strategy to synchronously boost the photoluminescence quantum yield and stability of CsPbBr3 PQDs by a sequential short-chain ligand (didodecyl dimethylammonium sulfide, DDA+-S2-) exchange and subsequent metal salt (In(Ac)3) treatment. From detailed characterization of the critical role of the metal ions, these enhancements were found to originate from the promoted ligand capping induced by the metal ions attached on the surface of the PQDs.

Enhancing the stability of CsPbBr nanocrystals by sequential surface adsorption of S and metal ions.

A sequential surface adsorption method for improving the photostability of perovskite nanocrystals (NCs) at room temperature was proposed. Firstly, S2- was decorated on the surface of CsPbBr3 NCs by adding didodecyl dimethylammonium sulfide (S2--DDA+), and then In3+ ions, which diffused from the salt powder of In(Ac)3, were slowly adsorbed by the pre-loaded S2-. Through this process, the photoluminescence quantum yield of the CsPbBr3 NCs increases from 57% to 80%, and their photostability, thermal stability, and colloidal stability were all drastically improved.

Postsynthesis Phase Transformation for CsPbBr/RbPbBr Core/Shell Nanocrystals with Exceptional Photostability.

Lead halide perovskite nanocrystals (NCs) as promising optoelectronic materials are intensively researched. However, instability is one of the biggest challenges needed to overcome before fulfill their practical applications. To improve their stability, we present a postsynthetic controlled phase transformation of CsPbBr toward CsPbBr/RbPbBr core/shell structure triggered by rubidium oleate treatment.

Conversion of invisible metal-organic frameworks to luminescent perovskite nanocrystals for confidential information encryption and decryption.

Traditional smart fluorescent materials, which have been attracting increasing interest for security protection, are usually visible under either ambient or UV light, making them adverse to the potential application of confidential information protection. Herein, we report an approach to realize confidential information protection and storage based on the conversion of lead-based metal-organic frameworks (MOFs) to luminescent perovskite nanocrystals (NCs). Owing to the invisible and controlled printable characteristics of lead-based MOFs, confidential information can be recorded and encrypted by MOF patterns, which cannot be read through common decryption methods.

Morphology Evolution and Degradation of CsPbBr Nanocrystals under Blue Light-Emitting Diode Illumination.

Under illumination of light-emitting diode (LED) or sunlight, the green color of all-inorganic CsPbBr perovskite nanocrystals (CPB-NCs) often quickly changes to yellow, followed by large photoluminescence (PL) loss. To figure out what is happening on CPB-NCs during the color change process, the morphology, structure, and PL evolutions are systematically investigated by varying the influence factors of illumination, moisture, oxygen, and temperature. We find that the yellow color is mainly originated from the large CPB crystals formed in the illumination process.

Transformation of metal-organic frameworks for molecular sieving membranes.

The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities.