Enhanced blue TADF in a D–A–D type naphthyridine derivative with an asymmetric carbazole-donor motif

Abstract

Efficient triplet-to-singlet conversion in conventional donor-acceptor TADF compounds relies on charge-transfer (CT) and locally-excited (LE) triplet state mixing as this provides required spin-orbit coupling. In this work, asymmetric carbazole-donor motif...

Synthetic progress of organic thermally activated delayed fluorescence emitters via C–H activation and functionalization

“…203 Building on these advancements, in 2022, Kazlauskas's group took advantage of the highly efficient synthetic method to access DCz and further prepared D-A, D-A-D (two same donors) and D-A-D* (two different donors) type blue-emissive TADF emitters (DCz-ND, DCz-ND-Cz and DCz-ND-DCz) with DCz as the common donor and naphthyridine as the common acceptor. 204 The intermolecular CÀH/ NÀH oxidation coupling in this study is a convenient synthetic method for the construction of a twisted donor motif that is suitable for designing TADF emitters.…”

Boosting Reverse Intersystem Crossing of TADF Emitter through Molecular Geometry Adaptation to Crystalline Host

“…[16] Following these principles, successful tailoring of the RISC rate has been achieved mainly through molecular engineering or by adjusting guest-host interactions. [17][18][19][20][21] For instance, the introduction of functional/steric groups has been demonstrated to induce CT-LE triplet state mixing [13,22] or cause more twisted configurations with reduced ΔE ST . [15,23] On the other hand, choosing the proper host polarity was shown to aid in aligning singlet and triplet manifolds in TADF guest, thereby also reducing the energetic barrier for RISC.…”

“…[ 11,12 ] To reduce the triplet lifetime in blue TADF devices, it is necessary to ramp up the RISC rate (k RISC ) while concurrently maintaining high radiative decay rates from the singlet state. Considering that the majority of reported blue TADF compounds exhibit k RISC similar to or below 10 6 s −1 , [ 13–15 ] this underscores the importance of a deeper insight into the TADF process. It also emphasizes the need for further development of molecules with rapid RISC, which is crucial for ensuring stable device operation at high current densities.…”

A spiroacridine-based thermally activated delayed fluorescence emitter for high-efficiency and narrow-band deep-blue OLEDs

“…Note that most TADF-OLED devices with l EL in the range of 455-465 nm have a CIE y value greater than 0.15. 20,27,28 Thus, the lower CIE y value of the SAC-BOC-based device is primarily attributed to its narrow-band emission (FWHM = 57 nm) through reasonable molecular design. Nonetheless, the relatively severe efficiency roll-off of the device could be observed, which is ascribed to the relatively slow RISC process.…”