Precisely Regulating the Electronic Structure Enables Highly Soluble, Luminescent, and Short‐Delayed Aluminum(III)‐TADF Complex for High‐Performance Solution‐Processed Green Hyperfluorescent OLEDs

Abstract Ubiquitous metal complexes with superior thermally activated delayed fluorescence (TADF) properties have emerged as promising candidates for light‐emitting materials due to their earth‐abundant nature and tunable optoelectronic characteristics. However, metal complexation often results in unfavorable solubility issues, which limit their application in solution‐processed OLEDs. Moreover, achieving a short‐delayed lifetime (τ d ) is essential for further enhancing device performance with a small efficiency roll‐off. In this work, a highly soluble and luminescent aluminum(III) complex exhibiting exceptional TADF characteristics is presented through precise regulation of their electronic structures. This complex demonstrates high solubility in common organic solvents while maintaining excellent photofunctional properties, such as PLQY values approaching unity, reduced aggregation‐caused quenching (ACQ), radiative decay rate constant ( k r ) exceeding 10 7 s −1 , impressive TADF performance with reverse intersystem crossing rate ( k RISC ) over 10 6 s −1 and τ d below 1 µs. Consequently, a novel aluminum(III) complex used as a sensitizer achieves an external quantum efficiency exceeding 20%, a full width at half maximum of 52 nm, and CIE coordinates of (0.31, 0.64) in solution‐processed hyperfluorescent OLEDs.