Carbonyl‐Containing Thermally Activated Delayed Fluorescence Emitters for Narrow‐Band Electroluminescence

Abstract

Carbonyl‐containing derivatives show enduring vitality in the field of thermally activated delayed fluorescence (TADF) materials; they can realize high device efficiency by using both singlet and triplet excitons for electroluminescence. Recently, a system based on fused ketone/amine exhibited huge potential for constructing multi‐resonance TADF (MR‐TADF) emitters, which exhibit higher narrow‐band emission than conventional TADF emitters with twisted donor‐acceptor (D‐A) structure. Herein, we summarize current research progress in both traditional and MR‐type ketone derivatives with TADF characteristics for introducing the molecular design strategy of maintaining high device efficiency while keeping narrow‐band emission profile. We hope this review can inspire the emergence of more high‐performance narrow‐band materials.

Narrowband emission: organic thermally-activated delayed fluorescence materials and underlying mechanisms

“…However, owing to distorted molecular conformations, those D–A type TADF generally show FWHMs broader than 50 nm. 37,38 Thus, those emitters are not concentrated in the following discussions.…”

“…However, owing to distorted molecular conformations, those D-A type TADF generally show FWHMs broader than 50 nm. 37,38 Thus, those emitters are not concentrated in the following discussions. 17 Those emitters consist of a triphenylborane core and two N atoms with phenyl disposed para to the central B atom (Fig.…”

“…The development of QAO (FWHM = 32 nm), the smallest TADF molecule reported to date, provides simple and versatile skeletons for designing various emitters. 38,57 However, originating from the feasible formations of ICT natures, CQO/N-based emitters generally suffer from broad emission profiles. For instance, the incorporation of different donors with varied electron-donating strengths has enabled a DiKTa-based series with wide-range emission FWHMs from 53 to 116 nm.…”

Sensitized organic light-emitting diodes: towards high efficiency and long lifetimes

“…However, serious efficiency roll-off and poor device lifetime have greatly limited their development. 10–12…”

“…However, serious efficiency roll-off and poor device lifetime have greatly limited their development. [10][11][12] Besides light-emitting materials engineering, introducing high exciton utilization materials such as phosphorescent, TADF, and exciplex materials as sensitizers into conventional emitters is an additional method to harvest triplet excitons (Fig. 1).…”