Achieving Tunable Monomeric TADF and Aggregated RTP via Molecular Stacking

Organic emitters with both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) have attracted widespread interest for their intriguing luminescent properties. Herein, a series of triphenylamine-substituted isoquinoline derivatives possessing monomeric TADF and aggregated RTP properties are reported. As the molecules exhibited various forms of π-π and charge transfer (CT) stacking with different intensities, inter/intramolecular CT can be meticulously modulated to achieve tunable TADF-RTP. Aggregated phosphorescence originates from intermolecular CT initiated by CT dimers, whereas monomeric TADF is facilitated by intramolecular CT enhanced by π-π dimers. Leveraging the properties of these molecules, luminescent materials with tunable TADF-RTP properties in multistates are obtained by molecular substitution position alignment, dealing with different solvents, grinding, adjusting concentration, changing polymer matrix, photoactivation, and heat treatment. This work is critical for a deeper understanding of construction and regulation of the TADF-RTP dual-channel emission, enabling the development of advanced optoelectronic devices with tailored emission properties.