Investigating the donor:acceptor ratio in thermally activated delayed fluorescence light-emitting macromolecules

Properties of Dual Emissive Dendrimers Based on ThermallyActivated Delayed Fluorescence Dendrons and a Phosphorescent Ir(ppy)3 Core

“…The first step in their syntheses was the preparation of the 2,4,6‐triphenyltriazine acceptor 1 , which was prepared in a 76% yield using an oxidative cyclization reaction between 4‐fluorobenzonitrile and 4‐bromobenzoylchloride. Acceptor 1 was then reacted with either 3,6‐bis[9,9‐di‐ n ‐propylfluorenyl]carbazole ( R 1 ) [ 8a ] or N 3 , N 6 ‐bis[4‐(2‐ethylhexyl)phenyl]‐ N 3 , N 6 ‐diphenyl‐9 H ‐carbazole‐3,6‐diamine ( R 2 ) [ 19 ] under S N Ar conditions to give the bromine functionalized intermediates 2 and 3 in yields of 48% and 77%, respectively. To form GD and BD , 2 and 3 were reacted with an excess of phenylboronic acid under standard Suzuki conditions, being isolated in yields of 96% and 95%, respectively.…”

“…A mixture of 1 (159 mg, 0.36 mmol), N 3 , N 6 ‐bis[4‐(2‐ethylhexyl)phenyl]‐ N 3 , N 6 ‐diphenyl‐9 H ‐carbazole‐3,6‐diamine [ 19 ] (560 mg, 0.79 mmol), caesium carbonate (611 mg, 1.87 mmol) in N,N ‐dimethylformamide (6 mL) was stirred in an oil bath held at 150 °C overnight under argon. The mixture was allowed to cool to room temperature and water (120 mL) was added.…”

“…The crude material was purified by size exclusion chromatography over Biobeads using toluene as eluent, followed by column chromatography using n-hexane:dichloromethane (2:1) as eluent to give 2 as a light-yellow powder (0.29 g, 48%). UV-vis: λ max (CH 2 Cl 2 )/nm 270sh (log ε/dm 3 mol −1 cm −1 5.17), 305 (5.30) [19] (560 mg, 0.79 mmol), caesium carbonate (611 mg, 1.87 mmol) in N,Ndimethylformamide (6 mL) was stirred in an oil bath held at 150 °C overnight under argon. The mixture was allowed to cool to room temperature and water (120 mL) was added.…”

“Flagella effect” of thermally activated delayed fluorescence emitter dominating the efficiency of non-doped solution-processed OLEDs

“…[11][12][13][14][15][16][17][18][19][20][21] Burn et al reported that 2-ethylhexyl surface groups acted as solubilizing groups for branched thermally activated delayed fluorescent (TADF) emitters to realize a maximum external quantum efficiency (EQE max ) of close to 10% for solution-processed OLEDs. 22 Besides, flexible chains can encapsulate the central organic chromophore to improve the emission efficiency. For example, Shao et al reported that an n-butoxy-encapsulated dendritic TADF emitter achieved an EQE max of up to 20.6% for solution-processed OLEDs, which was 2.0 times that of its tert-butyl-encapsulated counterparts.…”

Structure and Conformational Mobility of OLED-Relevant 1,3,5-Triazine Derivatives

“…Numerous studies have focused on devices based on polymers with an incorporated carbazole building block [ 18 , 19 , 20 , 21 ]. Carbazole derivatives are an effective host material for phosphorescent additives in PhOLEDs [ 15 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], an active component of fluorescent OLEDs with thermally activated delayed fluorescence (TADF) [ 14 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ] or molecules with a hybridized local and charge state of transfer (HLCT) [ 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. Computer-aided design is also currently being used to suggest more stable and more efficient organic diodes [ 51 ].…”