Enhancement of the electroluminescence properties of iridium-complexes by decorating the ligand with hole-transporting carbazole dendrons

Abstract

Iridium complexes are particularly essential and have been intensively utilized as emissive phosphorescence emitters for efficient phosphorescent electroluminescent (EL) devices. In order to improve the EL performance, a series of...

Red to orange thermally activated delayed fluorescence polymers based on 2-(4-(diphenylamino)-phenyl)-9H-thioxanthen-9-one-10,10-dioxide for efficient solution-processed OLEDs

“… 29 The first oxidation wave at E 1/2 of ∼0.91 V could be ascribed to the generation of radical cations on a donor moiety of the TADF fragment, while the second oxidation wave at E 1/2 of ∼1.11 V observed in the polymers PCTXO-F x could be assigned to the oxidation of the 3,6-di- tert -butylcarbazole pendant in the comonomer 3. 21 Apparently, as the content of monomer 5 in the polymers is reduced from PCTXO to PCTXO-F75, the currents of both reduction and first oxidation waves are steadily decreased, whereas the current of the oxidation wave at 1.11 V is gradually enhanced. The HOMO energy levels of PCTXO and PCTXO-F x in film state were then measured by UV photoelectron spectroscopy in air (Model AC-2) to be −5.50, −5.53, −5.56, and −5.69 eV, respectively ( Table 1 and Fig.…”

Efficient solution-processable deep-red hot exciton emitters based on thiadiazole[3,4-c]pyridine for a simple electroluminescent device

“…The reduction that occurred at a half-wave potential ( E 1/2 ) of −0.88 V was assigned to the formation of the radical anion of the bis(3-hexylthiophenyl) thiadiazole[3,4- c ]pyridine π-acceptor fragment, while the first oxidation that occurred at an E 1/2 value of 1.09 V was attributed to the formation of the radical cation of the carbazole dendron. 72 The HOMO energy level was deduced from the oxidation onset potential to be −5.46 eV and the LUMO energy level was calculated from the HOMO and E opt g to be −3.31 eV. The relatively low LUMO level of CTTPy is believably related to a high electron deficiency of the TPy moiety arising from its pyridine ring and the high electronegativities of the N and S atoms, while its high HOMO level is accredited to the electron-donating property of the end-capped carbazole dendrons.…”