In the field of perovskite light-emitting diodes (PeLEDs), the performance of blue emissive electroluminescence devices lags behind the other counterparts due to the lack of fabrication methodology. Herein, we demonstrate the in situ fabrication of CsPbClBr2 nanocrystal films by using mixed ligands of 2-phenylethanamine bromide (PEABr) and 3,3-diphenylpropylamine bromide (DPPABr). PEABr dominates the formation of quasi-two-dimensional perovskites with small-n domains, while DPPABr induces the formation of large-n domains. Strong blue emission at 470 nm with a photoluminescence quantum yield up to 60% was obtained by mixing the two ligands due to the formation of a narrower quantum-well width distribution. Based on such films, efficient blue PeLEDs with a maximum external quantum efficiency of 8.8% were achieved at 473 nm. Furthermore, we illustrate that the use of dual-ligand with respective tendency of forming small-n and large-n domains is a versatile strategy to achieve narrow quantum-well width distribution for photoluminescence enhancement.

A photonic-delay line is used as a frequency discriminator for measurement of the phase noise-hence the short-term frequency stability-of microwave oscillators. The scheme is suitable for electronic and photonic oscillators, including the optoelectronic oscillator, mode lock lasers, and other types of rf and microwave pulsed optical sources. The approach is inherently suitable for a wide range of frequency without reconfiguration, which is important for the measurement of tunable oscillators. It is also insensitive to a moderate frequency drift without the need for phase locking.

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Complex coacervation of polymers can be a route to the compartmentalization of aqueous solutions. Presented here is a study of the hydrogen-bonded complex coacervation of poly­(acrylic acid) and poly­(ethylene glycol) or Pluronic block copolymers and the ability of these coacervates to encapsulate various ionic and nonionic dyes as well as a pharmaceutical compound within them. The formation of complex coacervate driven by hydrogen bonding is studied as a function of both pH and salt content with turbidimetry and isothermal calorimetry. Small-angle X-ray scattering shows the presence of micelles within Pluronic containing coacervate materials formed with a Pluronic block copolymer concentration higher than its critical micelle concentration. Although dyes generally partition to the coacervate phase, in the absence of salt, dyes that are able to hydrogen bond with the coacervate components are better incorporated into the coacervate. It is observed that the addition of salt to the polymer solutions increases the hydrophobicity of the environment within the coacervate, increasing the ability to sequester dye molecules for which there is no hydrogen bonding with the coacervate components. These materials are characterized with UV–vis spectroscopy, dynamic light scattering, zeta potential measurements, isothermal calorimetry, small-angle X-ray scattering, and fluorescence spectroscopy.

Ferroelectricity in 2D metal phosphorus trichalcogenide heterostructures promotes charge separation and photocatalytic water splitting.

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