Metal‐free organic molecules with structurally diverse aggregation‐induced emission (AIE) behavior and new functional photophysical properties reveal unique structure–property relationships, especially bright luminescence, and have attracted extensive attention in the past few decades. Despite tremendous progress on fluorescent molecules development, the extended π‐conjugated organic AIE probes with their nanorange self‐assembly, coassembly, unique morphology, high biocompatibility, and light‐harvesting capabilities enable them as potential candidates in numerous translational application perspectives. In particular, a few important classes of AIE light up small molecules, supramolecules, oligomers, polymers, including nanoparticles and photosensitizer molecules, with their emerging properties of thermally activated delayed fluorescence, room temperature phosphorescence, including emission switching stimuli‐responsive behavior and multifunctional properties, have been boosted by the rare features of aggregation at their condensed or solid states. This review highlights salient features of AIE‐based emitters, encompassing molecular design strategies, stimulating photophysical properties, mechanistic aspects, and their efficacy in various electronic and biomedical applications, broadly covering properties of small molecules to oligomers, macromolecules to polymers.

Metal-free organic compounds with highly ordered π-conjugated twisted skeletons are capable of generating brilliant multi-colored light. Additionally, the co-existence of numerous other multi-functional properties have endowed them with the potential to be a promising class of materials for several electronic and photonic applications and next-generation advanced luminescent material-based devices. This review highlights the recent developments made in this fascinating class of multi-property encompassing materials, involving a highly twisted donor-acceptor based single molecular platform with synchronized photophysical behavior such as thermally activated delayed fluorescence (TADF), mechanoresponsive (MR), room-temperature phosphorescence (RTP), and aggregation induced emission (AIE) with associated unique and inherently manifested structure-property relationship investigations. Furthermore, a brief summary of the optoelectronic behavior of TADF materials are also presented by correlating their performances in the organic light-emitting diodes (OLEDs) and corresponding EL devices. In addition to mechanochromic luminescence (MCL) with TADF behavior, new types of emitters are also being developed, with tunable color changes such as blue-green, yellow-orange, yellow-red, etc., with some emitters crossing the entire visible span to produce white OLEDs. These developments have enriched the library of fascinating organic materials in addition to providing new directions of multifunctional material design for solutions processed OLED and several other advanced devices.

Thermally activated delayed fluorescence (TADF) emitters delivering an ability to harvest both electro-generated singlet and triplet excitons have resulted in faster radiative decay, saturated color purity, high photoluminescence quantum yield...

No abstract