Synthesis and properties of new derivatives of poly[9‐(2,3‐epoxypropyl)carbazole]

Abstract

BACKGROUND: Carbazole derivatives are well known to exhibit interesting electro-and photo-active properties due to their hole-transporting ability, strong absorption in the ultraviolet spectral region and blue-light emission. One of the most widely studied materials among carbazole-containing oligomers is poly[9-(2,3-epoxypropyl)carbazole] (PEPK). The main field of application of this oligomer is electrophotographic microfilming. It is also used for the manufacture of multicolour slides and in the photothermoplastic recording of information. Unfortunately, due to its high ionization potential, which reaches 5.86 eV, the possibilities of application of this compound in optoelectronic devices are rather limited. RESULTS: PEPK-based charge transporting oligomers, incorporating hydrazone moieties, are reported. The oligomers were prepared by chemical modification of PEPK. The materials obtained were examined using various techniques including differential scanning calorimetry and ultraviolet, infrared and NMR spectroscopy. Electron photoemission spectra of layers of the synthesized oligomers showed ionization potentials (I p ) in the range 5.4-5.5 eV. CONCLUSION:The synthesized oligomers possess a larger π -conjugated system and show ionization potentials of ca 5.4 eV. Therefore, they are more suitable for use in optoelectronic devices with quicker photoresponse than unmodified PEPK.

Triplet harvesting in poly(9‐vinylcarbazole) and poly(9‐(2,3‐epoxypropyl)carbazole) doped with CdSe/ZnS quantum dots encapsulated with 16‐(N‐carbazolyl) hexadecanoic acid ligands

“…As the excitation transfer from the excited carbazole monomer to the p‐ and f‐excimers could lower the energy transfer efficiency to the QDs either by blocking exciton hopping (both for singlet and triplet manifolds) or even blocking the direct excitation transfer from the excimer (for the triplet manifold) to the QDs, we wanted to modify the chemical structure of the polymer with carbazole side groups in a way to decrease excimer formation. As alternative to PVK we will therefore explore poly(9‐(2,3‐epoxypropyl) carbazole) (PEPK) as a polymer matrix for the QDs which shows less extensive excimer formation . Furthermore, it was reported for its advantages to have relatively low glass transition temperature and better film‐forming properties compared to PVK …”

“…As alternative to PVK we will therefore explore poly(9‐(2,3‐epoxypropyl) carbazole) (PEPK) as a polymer matrix for the QDs which shows less extensive excimer formation . Furthermore, it was reported for its advantages to have relatively low glass transition temperature and better film‐forming properties compared to PVK …”

“…As alternative to PVK we will therefore explore poly(9-(2,3-epoxypropyl) carbazole) (PEPK) as a polymer matrix for the QDs which shows less extensive excimer formation. [43][44][45] Furthermore, it was reported for its advantages to have relatively low glass transition temperature and better film-forming properties compared to PVK. 45 Figure 1(b) shows the PL spectra obtained upon excitation at 330 nm of a solution of PEPK in methyl-THF (77 K) and of a PVK film (RT) as well as the absorption spectrum of a solution of OA capped QDs in CB (RT).…”

“…[43][44][45] Furthermore, it was reported for its advantages to have relatively low glass transition temperature and better film-forming properties compared to PVK. 45 Figure 1(b) shows the PL spectra obtained upon excitation at 330 nm of a solution of PEPK in methyl-THF (77 K) and of a PVK film (RT) as well as the absorption spectrum of a solution of OA capped QDs in CB (RT). The PL spectrum of the solution of PEPK in methyl-THF at 77 K shows a band due to fluorescence of the carbazole monomer 16 (S 1 (monomer) !…”

Poly(2-(N-carbazolyl)ethyl acrylate) as a host for high efficiency polymer light-emitting devices

“…Among all phosphors 63 that have been investigated to date, iridium complexes 64 are undoubtedly the most widely studied. These com- 65 plexes have mostly been incorporated as neutral emitters 66 [6-15], but light-emitting devices have also been fabri- 67 cated with cations [16][17][18][19][20], anions [21,22] or soft salts 68 [23,24] where the anion and its cationic counterpart can 69 both participate in light emission when the two partners 70 are properly chosen. As an appealing feature, iridium com- 71 plexes exhibit relatively short excited state lifetimes so 72 that key adverse factors such as triplet-triplet annihilation http 74 strongly limited [25][26][27][28].…”