Volume 14 Issue 5, May 2015

Key materials discoveries have prompted the rise of inorganic light-emitting diodes in the lighting industry. Remaining challenges are being addressed to further extend the impact of this technology in lighting, displays and other applications.

Organic semiconducting molecules and colloidal quantum dots both make for excellent luminescent materials. Compared with the more established solid-state light-emitting technologies, organic LEDs and quantum-dot LEDs are in their infancy, yet they offer unique properties.

When efficient energy transfer under high carrier densities is required, two-dimensional nanoplatelets are the material of choice, combining an exceptional suppression of nonlinear fluorescence quenching with ultrafast transfer capabilities.

Using a scanning tunnelling microscopy-based method it is now possible to get an atomistic-level description of the most probable binding and contact configuration for single-molecule electrical junctions.

The finding of a new molecular phase in hydrogen under high pressure and moderate temperature adds to the complexity of its phase diagram.

A metal–organic framework with large pores catalytically destroys chemical warfare agents.

Porous silicon nanoneedles efficiently puncture cell monolayers, delivering biomolecules into cells both in vitro and in vivo.

An almost ideal quantum anomalous Hall state is observed in (Bi,Sb)Te films doped with vanadium. This state is reached without the application of a polarizing magnetic film, making these materials interesting for low-power electronic applications.

The resonant microwave excitation response of metals, semiconductors and insulating chiral magnets is studied by examining their entire magnetic phase diagrams, which includes the skyrmion lattice phase. A unified model to explain this response is also developed.

Fast fluorescence resonance energy transfer between CdSe nanoplatelets on a picosecond timescale is measured. This process is faster than Auger recombination and leads to the observation of multiexcitonic energy transfer in these materials.

A scheme of hybrid optical–electrical detection of an ensemble of donor electrons bound to phosphorus in silicon reveals electron spin Rabi oscillations and long coherence times, setting the foundations for a single-electron spin read-out technique.

Obtaining reliable high-pressure data from hydrogen at elevated temperatures presents considerable experimental challenges. It is now shown that a new phase transition occurs above 200 GPa as temperature increases, possibly indicating melting.

Using highly coherent interfaces of alternating oxide layers a bismuth-oxide-based oxygen ion conductor exhibits unprecedented high chemical stability in reducing conditions and during redox cycles at high temperature.

Visible-light-responsive photocatalysts can directly harvest energy from solar light. Stable conducting polymer nanostructures show high photocatalytic activity under visible light without using sacrificial reagents or precious metal co-catalysts.

A porous metal–organic framework with ultrawide channels and excellent chemical stability is now shown to be highly efficacious for the catalytic decomposition of chemical warfare agents containing phosphate ester bonds.

A method based on break-junction measurements to obtain information about the binding configuration of single-molecule junctions is reported. This approach also provides insight on how strain distributes along the molecule.

An approach that exploits two bioorthogonal photochemistries to achieve reversible immobilization of full-length proteins in synthetic hydrogels allows for the reversible differentiation of human mesenchymal stem cells to osteoblasts.

Efficient in vivo cytosolic delivery of nucleic acids through cell-membrane puncturing by an array of biodegradable silicon nanoneedles induces sustained local neovascularization in muscle.

Light-emitting diodes are transforming the lighting industry and play a primary role in high-tech displays and other applications. This focus issue highlights the materials and technological advances that contributed to the success of these light sources, and discusses the future prospects and challenges of this technology.