Structure–properties relationship of carbazole and fluorene hybrid trimers: experimental and theoretical approaches

Abstract

Synthesis and properties of fluorene and carbazole derivatives having three electrophores per molecule with different architectures are reported. The synthesized compounds possess high thermal stabilities with 5% weight loss temperatures exceeding 350 °C. They form glasses with glass transition temperatures ranging from 60 to 68 °C. Cyclovoltammetric experiments revealed the high electrochemical stability of the fluorene trimer. In contrast, 2- and 2,7-fluorenyl substituted carbazole derivatives show irreversible oxidation in the CV experiments. The electron photoemission spectra of the films of the synthesized compounds revealed ionization potentials of 5.65-5.89 eV. Hole drift mobilities in the amorphous layers of the synthesized compounds reach 10(-2) cm(2) V(-1) s(-1) at high electric fields, as established by a xerographic time-of-flight technique. DFT calculations show that HOMO and LUMO orbitals of the compounds are very similar in energy and shape. The similar hole mobilities observed for the three compounds are discussed in the frame of the Marcus theory. An important influence of the alkyl groups on the ionization potentials and on the hole mobilities was also observed and its origin is discussed.

Photophysics, Electrochemistry, Morphology, and Bioimaging Applications of New 1,8‐Naphthalimide Derivatives Containing Different Chromophores

“…Owing to bulkiness, dye 5 b exhibits the highest T d value among the series. Furthermore, carbazole‐bearing dyes 4 b and 5 c show higher thermal stability than fluorene analogues 4 a and 5 a , which is in line with literature precedent …”

“…Though a chromophore attached to the nitrogen atom has negligible or no influence on the electronic properties that are otherwise dominated by the naphthalimide core, they help to modulate the interchromophoric interactions in the solid state and, consequently, the charge‐transporting properties. Among the pool of aromatic electron‐rich chromophores, carbazoles, triphenylamines, and fluorenes are widely explored because of their easy oxidizability and their ability to transport charges via radical‐cation species. Integration of a hole‐transporting moiety with an electron‐transporting unit is beneficial to balance charge transport in the molecular layer.…”

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

“…LUMO energies of the four compounds are thus in the order of −4.20 eV for compounds 2 and 5 and −4.30 eV for compounds 3 and 4 (Table 1). At positive potentials, the two diphenylamine derivatives ( 2 and 5 ) showed reversible one-electron oxidation waves, while the two carbazole donor derivatives ( 3 and 4 ) showed irreversible oxidation waves, which is a function of the electrochemically unstable carbazole-based radical cation that can subsequently undergo dimerization [34]. The oxidation waves shifted cathodically upon increasing the donor strength from carbazole ( 3 and 4 ) to diphenylamine ( 2 and 5 ).…”

Investigation of Abnormal Long‐Wavelength Fluorescence Emissions Occurring in Binary Organic Nanoparticle Films

“…Besides a fluorene unit, DNAPFB also has planar and rigid anthracene and naphthalene groups in its molecular structure. Because carbazole is more resistant to oxidation than fluorene, we chose DPFL‐CBP with two carbazole groups at the 2,7‐positions of the central fluorene unit as a contrast to TDAF. DPFL‐TPD is an analogue of DPFL‐CBP but has two non‐planar diphenylamine moieties instead of the planar carbazole groups at the 2,7‐positions of the central fluorene unit.…”