Dual Emission: Classes, Mechanisms and Conditions

Dual emission materials have found much interest in the past years for materials and life science applications; however, a systematic overview on the underlying processes is missing by now. This is done herein, classifying dual emission (DE) phenomena, relying either on one emitter with two emitting states (DE1), two independent emitters (DE2), or two correlated emitters (DE3). Relevant DE mechanisms for materials science are then briefly described, giving the electronic and/or geometrical conditions under which they occur; for further reading, reference to reviews and textbooks is given, which offer detailed insight into the complex mechanistic aspects of the various DE processes, provide overviews on materials' families, or their applications. Avoiding ambiguities and misinterpretations, this systematic, insightful tutorial review might inspire future targeted design of DE materials.