Topological Arrangement of Fluorenyl-Substituted Carbazole Triads and Starbursts: Synthesis and Optoelectronic Properties

Diphenylaminocarbazoles by 1,8-functionalization of carbazole: Materials and application to phosphorescent organic light-emitting diodes

“…Both the solution and thin film spectra are nearly identical. The absorption pattern of the three compounds is mutually similar as shown by the spectra, having similarity with the 1,8-fluorenyl substituted carbazoles [31]; particularly, the absorption spectra of DPACz1 and DPACz2 are similar showing there is no particular change in the absorption with the increase in the no. of diphenylamine unit at positions 1 and 8 of carbazole.…”

“…The monobromo intermediate (4) was prepared by first bromination of (1) with NBS to get (2) [41] followed by N-alkylation with bromoethane in the presence of NaOH in acetone [42]. It is important to mention here that this pathway for the preparation of (4) was found to be much easier as compared to the previously reported method [31] of doing Nalkylation first and then bromination which resulted into the formation of both mono-and dibromocarbazoles, (4) and (5) respectively, which were not easily separable by column chromatography (due to very close R f values) or by recrystallization (due to quite similar solubilities). In our method although the bromination of (1) using 1:1 molar ratio of the reactant and NBS resulted into the appearance of the 1,8-dibromocarbazole as a very small impurity but the R f values of the two bromocarbazoles with free 'NH' group were much different to allow easy purification of (4) by column chromatography.…”

“…However, carbazoles with substituents at 1-and 8-positions have been relatively rarely reported [25e30], particularly for their use in OLEDs [31,32]. Substitutions at 1-and 8-positions of carbazole occur once the more active positions i.e.…”

“…Carbazole-based triarylamines such as those obtained by appending diphenylamino units at 3-, 6-[34e37] and 2-, 7-positions [38,39] have been reported previously for their hole transport properties, but to the best of our knowledge, no report is there for carbazoles with diphenylamino-units appended at only 1-and 8-positions and the use of such materials for OLED applications. Regarding the importance of substituents at 1-and 8-positions of carbazole with respect to the host materials, it has been found that substitution at 1-and 8-positions results into materials with higher triplet energy levels than those with substitution at 2-,7-or 3-,6-positions [31]. It is intriguing, therefore, to further elaborate the substituent effect at 1-and 8-positions of carbazole system using functionalities having good charge transport properties such as diphenylamino for their use as host as well as hole transport materials in OLEDs.…”

Sulphonate anchored hemicyanine dyes for dye solar cell: A study on dipole moment and polarity

“…5,6 cyanine, 7,8 carbazole, [9][10][11] coumarin, [12][13][14] perylene, 15,16 merocyanine, 17,18 indoline, [19][20][21] and hemicynine [22][23][24] based organic dyes have been studied as sensitizers in DSSC with good photoconversion efficiencies (PCEs). Among them, hemicyanine dyes with donor (D) and acceptor (A) separated by p-bridged structure (D-p-A) are promising photosensitizers, capable to produce a charge-separated exited state upon photoinduced intramolecular charge transfer.…”