Luminescent Materials: Metal Complexes, Clusters, and Nanomaterials

Abstract

Although the first reports on fluorescence and phosphorescence dated back to the 16th century, [1,2] the term "luminescence", originating from the Latin "lumen" meaning light, was only introduced in 1888 by the German physicist Eilhardt Wiedemann to encompass all the phenomena where light is produced by means other than heating.[1] Probably because it is related to our most important sense, sight, luminescence has fascinated generations of scientists; famous names such as Stokes, Kasha, Jablonsky, Becquerel(s), and many others have made impressive contributions in the field of photon emission. The pioneering works by these scientists are the cornerstones of the understanding of luminescence phenomena and opened the way to technological advances that boosted the field. The 20th century was particularly rich in such breakthroughs, including the development of powerful light sources and lasers, [3] monochromators for enhanced spectral resolution, [4] and sensitive photomultipliers for optical detection.[5] With the availability of commercial spectrophotometers in laboratories in the mid-1950s, it became easier to record and compare luminescence signals and the different pathways for photon generation upon an input of energy. While the earlier works focused essentially on the studies of the two ends of matter in terms of size, namely minerals/bulk solids and small organic/inorganic molecules, recent decades have witnessed the merging of these areas and the development of new luminescent nanomaterials and molecules. Examples include quantum dots (QDs), lanthanide nanoparticles (NPs), metal clusters, and many others, which shine like new stars in the sky of chemists, physicists, and spectroscopists, offering new avenues and applications in chemical, environmental, materials, and biological sciences.With such a long history and diverse areas of research, it is impossible to deliver a survey of luminescent compounds. Instead, our approach was to gather contributions from recognized colleagues in various fields of luminescent materials. We are grateful to all of them and their co-authors for their valuable contributions in this cluster issue and for shedding some new light on these rapidly emerging areas of research.[a]