A Deep‐Blue‐Emitting Heteroatom‐Doped MR‐TADF Nonacene for High‐Performance Organic Light‐Emitting Diodes**

Abstract

We present a p-and n-doped nonacene compound, NOBNacene, that represents a rare example of a linearly extended ladder-type multiresonant thermally activated delayed fluorescence (MR-TADF) emitter. This compound shows efficient narrow deep blue emission, with a λ PL of 410 nm, full width at half maximum, FWHM, of 38 nm, photoluminescence quantum yield, Φ PL of 71 %, and a delayed lifetime, τ d of 1.18 ms in 1.5 wt % TSPO1 thin film. The organic lightemitting diode (OLED) using this compound as the emitter shows a comparable electroluminescence spectrum peaked at 409 nm (FWHM = 37 nm) and a maximum external quantum efficiency (EQE max ) of 8.5 % at Commission Internationale de l'Éclairage (CIE) coordinates of (0.173, 0.055). The EQE max values were increased to 11.2 % at 3 wt % doping of the emitter within the emissive layer of the device. At this concentration, the electroluminescence spectrum broadened slightly, leading to CIE coordinates of (0.176, 0.068).

Integrating Asymmetric O−B−N Unit in Multi‐Resonance Thermally Activated Delayed Fluorescence Emitters towards High‐Performance Deep‐Blue Organic Light‐Emitting Diodes

“…Moreover, benefited by the higher PLQY of ODBN , the corresponding device exhibited considerably high EQE of 24.15 %, maximum current efficiency (CE) of 9.17 cd m −2 and maximum power efficiency (PE) of 8.02 lm W −1 (Figure 4c and d). The CE and PE are lower than the EQE because the actual emitted photon number is more than the measured value in the deep blue light‐emitting devices [53] . To the best of our knowledge, the remarkable device efficiencies are among the best results of reported deep‐blue OLEDs with the CIE y below 0.10.…”

“…The CE and PE are lower than the EQE because the actual emitted photon number is more than the measured value in the deep blue light-emitting devices. [53] To the best of our knowledge, the remarkable device efficiencies are among the best results of reported deep-blue OLEDs with the CIE y below 0.10. Moreover, NBN-based OLED device also gave an excellent performance with high EQE of 23.02 %, but poor performance was found in OBNbased OLED with EQE of 15.7 % owing to the weak MR-TADF property and low PLQY (Figure 4c and d).…”

Recent progress and prospects of fluorescent materials based on narrow emission

“…4r) with nine six-membered rings fused along one dimension. 53 In THF solution, NOBNacene exhibited deep-blue emission with a λ PL of 405 nm, an FWHM of 40 nm and a PLQY of 33%. In 1.5 wt% TSPO1 films, NOBNacene showed a PLQY of 71% with a delayed exciton lifetime of 1.77 ms in the emission of the deep blue region.…”

“…4 (a-y) Chemical structures of emitters discussed in Section 3.1.1. 26,[32][33][34][38][39][40][41][42][43][44][47][48][49][50][51][52][53][54][55][56][57][58][59] This journal is © The Royal Society of Chemistry 2023…”

One-Shot Construction of BN-Embedded Heptadecacene Framework Exhibiting Ultra-narrowband Green Thermally Activated Delayed Fluorescence

“…The most promising way to utilize the MR effect is to extend it to a fully resonating π-skeleton with multiple boron and nitrogen atoms . Therefore, we have developed the one-shot borylation reaction in our previous study, which involved inter- and intramolecular tandem bora-Friedel–Crafts reactions (electrophilic C–H borylation) . However, the borylation reaction is accompanied by a decrease in HOMO energy and insolubilization of the resulting intermediate and therefore only proceeds up to three times with one exception…”