Recent Progress of Thermally Activated Delayed Fluorescent Materials with Narrowband Red, Green, and Blue (RGB) Emission

Narrowband thermally activated delayed fluorescence (TADF) materials have received widespread attention due to their promising applications in organic light-emitting diodes with high-definition displays. Great efforts have been done to achieve full-color narrowband emissions in donor–acceptor (D–A) and multiple-resonance (MR) TADF materials. In comparison with the D–A TADF materials, the MR-based materials basically showed smaller the full width at half-maximum (fwhm) of spectra owing to the inherent structural vibration inhibition and electronic transition characteristics. Herein, the review summarizes the current research progress on both narrowband D–A and MR TADF materials in blue, green and red emission regions with the fwhm less than 70 nm concentrating on the molecular design strategies, the photophysical properties and corresponding device performance, and proposes some possible future research topic. This review aims to give some physical insight on the structure–property relationship of such materials, offer some guidance for the further developing narrowband TADF materials, and provide a structured database platform for further high-throughput or machine learning research.