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The last decade has witnessed extensive breakthroughs and significant progress in atomically flat two-dimensional (2D) semiconductor nanoplatelets (NPLs) in terms of synthesis, growth mechanisms, optical and electronic properties and practical applications. Such NPLs have electronic structures similar to those of quantum wells in which excitons are predominantly confined along the vertical direction, while electrons are free to move in the lateral directions, resulting in unique optical properties, such as extremely narrow emission line width, short photoluminescence (PL) lifetime, high gain coefficient, and giant oscillator strength transition (GOST). These unique optical properties make NPLs favorable for high color purity light-emitting applications, in particular in light-emitting diodes (LEDs), backlights for liquid crystal displays (LCDs) and lasers. This review article first introduces the intrinsic characteristics of 2D semiconductor NPLs with atomic flatness. Subsequently, the approaches and mechanisms for the controlled synthesis of atomically flat NPLs are summarized followed by an insight on recent progress in the mediation of core/shell, core/crown and core/crown@shell structures by selective epitaxial growth of passivation layers on different planes of NPLs. Moreover, an overview of the unique optical properties and the associated light-emitting applications is elaborated. Despite great progress in this research field, there are some issues relating to heavy metal elements such as Cd2+ in NPLs, and the ambiguous gain mechanisms of NPLs and others are the main obstacles that prevent NPLs from widespread applications. Therefore, a perspective is included at the end of this review article, in which the current challenges in this stimulating research field are discussed and possible solutions to tackle these challenges are proposed. [ABSTRACT FROM AUTHOR]

The interface states have significant effects on the optoelectronic properties of quantum dot-based light emitting diodes (QLEDs). Herein, we employed a dielectric interlayer, namely, phenylethylammonium bromide (PEABr):methylammonium bromine (MABr), in indium phosphide (InP) QLEDs to modulate the interfacial charge transfer via inducing the formation of interface dipoles. The PEABr:MABr interlayer was deposited between the electron transport layer (ETL) of MgZnO (MZO) nanoparticles and the metal Al cathode to simultaneously enhance the ETL/Al interfacial contact for minimizing the contact resistance and modifying the conduction band minimum (CBM) of the ETL to prevent the over injection of electrons, leading to improved charge balance within the QLEDs. Besides, the surface defects on the MZO ETL can be passivated with the aid of Br filling, favoring the enhancement of the radiative recombination efficiency in the QDs of the emitting layer (EML). As a result, the efficiency and the operational lifetime of the resultant green InP QLED are enhanced by more than 2-fold and 9-fold, respectively, achieving a maximum external quantum efficiency (EQE) of 7.8% and an operational lifetime of over 400 h. [ABSTRACT FROM AUTHOR]

Metal halide perovskite light-emitting diodes (PeLEDs) have aroused extensive attention due to their high color purity, wide color gamut, and low-cost solution processability, showing great potential for application in next-generation high-definition display and solid-state lighting. Recently, the external quantum efficiencies (EQEs) for PeLEDs have impressively exceeded 20%; however, they were all achieved in laboratory-scale devices (<0.1 cm2). With scaling up device area, the efficiency will be reduced dramatically by the non-uniformity of large-area perovskite layers because the generated pinholes or cracks increase defect-induced nonradiative recombination and lead to current leakage. The development of large-area PeLEDs (≥1 cm2) is challenged by the difficulty in preparing dense and uniform perovskite thin films on large scale. In this Perspective, we briefly introduce the basic features of perovskite materials and systematically summarize the fabrication technologies for large-area perovskite films; we then present the recent advances in large-area PeLEDs. Finally, the challenges and opportunities for further enlarging the active emission area of PeLEDs are discussed. [ABSTRACT FROM AUTHOR]

We, for the first time, correlated the alkyl chain length of amine molecules with the defect passivation efficacy, either on the surfaces or at grain boundaries of perovskite films. Blade-coated perovskite solar cells with long-chain amine passivation achieved an efficiency of 21.5%, accompanied by a small voltage loss of 0.35 V. [ABSTRACT FROM AUTHOR]

Herein, we report a modular synthetic approach of (C-10 to C-13)-substituted 9,14-diaryl-9,14-dihydrodibenzo[a,c]phenazine derivatives. This synthetic route enables the aromatic substitution in a predictable and programmed manner to obtain products in synthetically useful isolated yield. [ABSTRACT FROM AUTHOR]

For the first of time, we demonstrate that methylammonium cadmium halides show photoelectrochemical (PEC) response with excellent humidity and chemical resistance because the oxidation state of almost all cadmium compounds is +2. The photocurrent densities of two-dimensional (2D) layered (MA)2CdCl4 perovskites are about 0.30 mA cm−2 under 100 mW cm−2 irradiation. The interaction between these methylammonium cadmium halides and water vapor is studied by probing film morphology and characterizing single crystal structure. It is shown that H2O is able to complex with the perovskite, forming a hydrate product with the molecular formula of MACd3Cl7·3H2O upon humidity exposure. This causes a decrease in absorption and a recognizable change in the crystal structure of the material. When compared to methyl-ammonium lead iodide (MAPbI3), the PEC stability of 2D layered (MA)2CdCl4 perovskites with BQ/BQṖ− redox couples (where BQ is benzoquinone) in CH2Cl2 is enhanced from 50 hours to 600 hours, exhibiting an increase of 12 times. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic halide perovskites have been extensively studied due to their remarkable optical and electronic features, such as high absorption coefficient, long exciton diffusion length, excellent carrier transport and low exciton binding energy, as well as a facile solution process for the fabrication of organic–inorganic halide perovskites. High-efficiency solar cells with methylammonium lead halide perovskites have been successfully achieved within just a few years. The high-quality perovskite films have made a significant impact on the fabrication of efficient and stable hybrid perovskite solar cells. Morphology engineering has been recognized as an effective way to obtain highly crystalline and pinhole-free perovskite films with optimized grain sizes. Here, we summarize several methodologies of morphology engineering, consisting of additive engineering, self-assembled monolayers (SAMs), solvent engineering, solvent annealing, thermal engineering, compositional engineering and humidity engineering. The highly crystallized perovskite layers prepared by using these techniques show a uniform surface morphology, resulting in enhanced photovoltaic efficiency and long-term stability of hybrid perovskite solar cells. [ABSTRACT FROM AUTHOR]

Correction for 'Atomically flat semiconductor nanoplatelets for light-emitting applications' by Bing Bai et al., Chem. Soc. Rev., 2023, 52, 318–360, https://doi.org/10.1039/D2CS00130F. [ABSTRACT FROM AUTHOR]

N-Substituted aminomethylphenol (Mannich base) and 3,4-dihydro-2H-3-substituted 1,3-benzoxazine (benzoxazine) were synthesized from substituted phenol (p-cresol, phenol, p-chlorophenol), substituted aniline (p-toluidine, aniline, p-chloroaniline) and formaldehyde to study influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde. 1H-NMR and charges of nitrogen and oxygen atoms illustrate effect of substituent on reactivity of Mannich base, while oxazine ring stability is characterized by differential scanning calorimetry (DSC) and C–O bond order. Equilibrium constants were tested from 50 °C to 80 °C, and the results show that substituent attached to phenol or aniline has same impact on reactivity of Mannich base; however, it has opposite influence on oxazine ring stability and equilibrium constant. Compared with the phenol–aniline system, electron-donating methyl on phenol or aniline increases the charge of nitrogen and oxygen atoms in Mannich base. When the methyl group is located at para position of phenol, oxazine ring stability increases, and the equilibrium constant climbs, whereas when the methyl group is located at the para position of aniline, oxazine ring stability decreases, the benzoxazine hydrolysis tends to happen and equilibrium constant is significantly low. [ABSTRACT FROM AUTHOR]

This communication describes the synthesis of Pt@CeO2 core–shell catalysts for the application of highly efficient CO oxidation, where the 50% CO conversion temperature is lower than 200 °C. Pt@CeO2 is thermally stable as no deactivation occurs during the 70 h reaction, and the morphology is unchanged even after 700 °C thermal treatment. [ABSTRACT FROM AUTHOR]

This communication describes the design and synthesis of anti-sintering and -coke nickel phyllosilicate (PS) nanotubes (Ni/PSn) for hydrogen production via reforming reactions. The introduction of nickel particles in PS nanotubes could effectively maintain the Ni size and increase the resistance of metal particles for carbon deposition. [ABSTRACT FROM AUTHOR]

This communication describes the synthesis of a nanocomposite Ni@ZrO2 catalyst with enhanced metal–support interaction by introducing metal nanoparticles into the framework of the oxide support. The catalyst shows high catalytic activity and stability for hydrogen production via steam reforming of ethanol. [ABSTRACT FROM AUTHOR]

This communication describes the synthesis of a nanocomposite Ni@ZrO2 catalyst with enhanced metal-support interaction by introducing metal nanoparticles into the framework of the oxide support. The catalyst shows high catalytic activity and stability for hydrogen production via steam reforming of ethanol.

This paper describes a strategy for producing hydrogen via steam reforming of ethylene glycol over supported nickel catalysts. Nickel plays a crucial role in conversion of ethylene glycol and production of hydrogen, while oxide supports affect product distribution of carbonaceous species. A plausible reaction pathway is proposed based on our results and the literature.

This paper describes the utilization of skeletal Ni-based catalysts for steam reforming of ethanol to produce CO-free hydrogen, which could be superior in the application of fuel cells. Assistant metals play different roles in the reaction; Pt and Cu suppress the methanation and enhance H(2) production, while Co promotes the methanation.