Dual Emission: Classes, Mechanisms, and Conditions

Abstract

There has been much interest in dual-emission materials in the past few years for materials and life science applications;h owever, asystematic overview of the underlying processes is so-far missing.We resolve this issue herein by classifying dual-emission (DE) phenomena as relying 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 together with the electronic and/or geometrical conditions under which they occur.F or further reading,references are given that offer detailed insight into the complex mechanistic aspects of the various DE processes or provide overviews on materials families or their applications. By avoiding ambiguities and misinterpretations,t his systematic, insightful Review might inspire future targeted designs of DE materials.

Full-colour solvatochromic fluorescence emitted from a semi-aromatic imide compound based on ESIPT and anion formation

“…For instance, dual emission can be obtained one emitter with two emitting states, two independent emitters, or two correlated emitters, and their mechanisms and the electronic or geometrical conditions have been investigated for molecular design and applications. Such materials have been of great interest over the past few years [7,8]. In recent years, aromatic imide/amide molecules have attracted significant attention because of their excellent photothermal and chemical stabilities with rigid structures, high-fluorescence quantum yields, and characteristic electron-transporting properties [9].…”

A color-tunable single-component luminescent molecule with multiple emission centers

“…Except for phosphors, delayed fluorescence had also be used in developing dynamically controlled afterglow [18][19] . Therefore, the different expressions of triplet excitons provide a high possibility to achieve colorful emissions in single-component materials [20][21] . However, the strategies based on triplet excitons controlling to tune emission colors are still rare and short of regularity.…”

Metal‐Free Organic Luminophores that Exhibit Dual Fluorescence and Phosphorescence Emission at Room Temperature

“…Therefore, the development of precious-metal-free organic luminophores that exhibit bimodal and balanced dual emission of fluorescence and phosphorescence in the solid state at RT is one of the most intriguing subjects in the field of light-emitting materials science from the viewpoint of molecular engineering for the purpose of controlling triplet excited states, as well as that of practical applications that are difficult to achieve with solely fluorescent or phosphorescent materials. [11] In this Minireview, we survey photoluminescent properties and applications of metal-free dual-emissive compounds, classified into six categories according to their structure, which dictates luminescence: difluoroboron diaroylmethanes, diarylketones, diarylsulfones, triazines and pyrimidines, fused phenazines, and N-arylcarbazoles ( Figure 3). To describe the character-istics of luminescence bimodal spectra (whether fluorescence or phosphorescence is more intense), spectra wherein the intensity of the fluorescence peak (I F ) is higher than that of phosphorescence (I P ), are termed type I (Figure 2b), while spectra wherein I P is higher than I F , are denoted as type II (Figure 2c).…”