Probing semiconductor crystals with a sphere of light

Tohoku University researchers have developed a technique using a hollow sphere to measure the electronic and optical properties of large semiconducting crystals. The approach, published in the journal Applied Physics Express, ...

Missing atoms in a forgotten crystal bring luminescence

A little-studied member of the perovskite family of materials could find use in a range of electronic devices, after researchers at KAUST discovered the secret of its strong photoluminescence.

Coming to a monitor near you: A defect-free, molecule-thick film

An emerging class of atomically thin materials known as monolayer semiconductors has generated a great deal of buzz in the world of materials science. Monolayers hold promise in the development of transparent LED displays, ...

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Photoluminescence (abbreviated as PL) is a process in which a substance absorbs photons (electromagnetic radiation) and then re-radiates photons. Quantum mechanically, this can be described as an excitation to a higher energy state and then a return to a lower energy state accompanied by the emission of a photon. This is one of many forms of luminescence (light emission) and is distinguished by photoexcitation (excitation by photons), hence the prefix photo-. The period between absorption and emission is typically extremely short, in the order of 10 nanoseconds. Under special circumstances, however, this period can be extended into minutes or hours.

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