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Procedure of post-functionalization by carbazole or phenothiazine of dicyanopyridines was developed. Pyridine ring in new pyridines exists in a twist-conformation in solid state. Green and orange thermally activated delay fluorescence...

With the aim of developing all-organic bipolar semiconductors with high chargem obility and efficient Etype fluorescence(so-called TADF) as environmentally friendly light-emitting materials for optoelectronica pplications, four noble metals-free dyes with linear and V-shapesw ere designed usinga ccepting pyridine-3,5-dicarbonitrile and donating carbazole units. By exploiting ad onor-acceptor design strategya nd using moieties with different donating and accepting abilities,T ADF emitters with aw ide variety of molecular weights were synthesized to achievethe optimum combination of charge-transporting and fluorescent properties in one TADF molecule. Depending on molecule structures, differentT ADF emittersc apable of emitting in the range from 453 to 550 nm with photoluminescenceq uantum yields up to 98 %f or the solutions in oxygen-free toluene wereo btained. All compounds showedb ipolar chargetransport. Hole mobility of 2.8 10 À3 cm 2 /Vs at 7 10 5 Vcm À1 was observedf or the compound containing two di-tertbutyl-substituted carbazole moieties. The compounds were testedi nb oth non-doped and dopedo rganic light-emitting diodesu sing different hosts.I tw as shown that the developed TADF emitters are suitable for different color devices with electroluminescence ranging from blue to yellow and with brightness, maximum current and external quantum efficiencies exceeding 10 000 cd m À2 ,1 5cd/A, and 7%,r espectively.