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A series of random copolymers of 2,7-dibromo-9,9-bis(4′-n-octyloxyphenyl) fluorene (BOPF) and 2,7-dibromo-N-(2′-ethylhexyl)carbazole (EHC) were synthesized through Ni(0)-mediated polymerization. Carbazole comonomer was introduced to improve the hole-transporting properties of PBOPF. The synthesized poly(BOPF-co-EHC)s showed similar UV-visible absorption and PL emission to PBOPF. EL devices were fabricated in an ITO/PEDOT/polymer/Ca/Al configuration. EL devices which used copolymers showed improved device performance over devices which used PBOPF homopolymers due to a more balanced charge transport.

We synthesized and characterized novel highly phenyl-substituted spirobifluorene and carbazole derivatives such as 3,6-bis[(2,3,4,5-tetraphenyl)phenyl]-9-ethylcarbazole (BTPEC); 3,6-bis(7,10-diphenyl-fluoranthene)-9-ethylcarbazole (BDFEC); 2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,9′-spirobifluorene (BTPSF); and 3,6-bis(7,10-diphenyl-fluo-ran-thene)-9,9′-spirobifluorene (BDFSF), through Diels–Alder reaction. BDFEC showed sky blue PL spectrum at 481 nm and BTPSF showed ultra-violet PL spectrum at 374 nm in chloroform solution. Also BTPEC and BDFSF exhibited PL spectrum at around the UV region, 390 and 467 nm.

Polyazomethine-type conjugated polymers were synthesized by Schiff-base reaction. One was poly(PZ-PBI) with alternating phenothiazine (PZ) and azomethine units (-C = N-), and the other was poly(CZ-PBI) comprising alternating carbazole (CZ) and azomethine groups. Conjugated polymers exhibited improved solubility in common organic solvents due to alkyl side chains on phenothiazine and carbazole rings as well as polar azomethine groups in main chains. Single- and double-layer PLEDs were fabricated. Their electroluminescent properties were studied from the viewpoint of polymer structure vs. emission color and efficiency.