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Four different types of alternating copolymers, named as poly(N-(2-ethylhexyl)-3,6-dibromo-carbazole-alt-aniline) (P1), poly(3,6-dibromo-carbazole-alt-aniline) (P2), poly(N-(3,5-dibromo-methylene-phenyl)-carbazole-alt-aniline) (P3) and poly(N-[4-(2-ethylhexyloxyl)-3,5-dibromomethylene-phenyl]-carbazole-alt-aniline) (P4) were successfully synthesized by palladium-catalyzed polycondensation of corresponding carbazole-containing dibrominated compounds and an aniline. These resulting polymers exhibited good solubility in normal organic solvents and showed relatively high molecular weights. Excellent thermal stability of the polymers was observed from TGA, showing less than 8% of weight loss on heating to 350°C under N₂ atmosphere. From UV-Vis absorption and photoluminescence spectra of these solution-processable polymers, it was observed that λ_max,UV was in the range of 308 – 352 nm and λ_max,PL was in the blue emission range of 450 – 463 nm. Electrochemical characteristics of these alternating copolymers were investigated to prove the potential in application for blue-emitting host matrix and hole-transporting layer in polymer light-emitting devices.

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.

Carbazole compounds have been proven to exhibit vital photophysical and biological applications. Even simple carbazole derivatives were showing attractive biological activities such as antimicrobacterial activity (Glycozoline), antiproliferative activity (Mukonine), free radical scavenger (Carazostatin), etc. In case of photophysical applications, carbazole derivatives were utilized in organic semiconductors, photoconducting polymers, Green host material in phosphorescent organic light-emitting diodes (OLEDs), hole-transporting material in OLEDs and organic light emitting materials. An account of different synthetic methodologies involved in the synthesis of natural and synthetic carbazole derivatives was evaluated based on the usage of commercially available cheap starting materials such as derivatives of Indole. This paper takes into account the time from 2011 to 2023. The advanced methods were developed based on the 12 principles of Green chemistry such as Multistep domino reactions, Atom & Step economy reactions, protection-free reactions, mild reaction conditions, open atmosphere reactions, harmless by-products and photochemical transformations.