A new small-molecular thermally cross-linkable material {[4-(9-phenyl-9H-carbazol-4-yl)phenyl]-bis-(4′-vinylbiphenyl-4-yl)-amine} (PCP-bis-VBPA, PbV) containing the styrene moiety was synthesized for hole transport layers in wet processed organic light-emitting diodes (OLEDs). It was found that PbV exhibited relatively high glass temperatures above 154 °C and a triplet energy (T 1 ) greater than 2.81 eV. This new synthetic hole transport material (HTM) forms very uniform films after crosslinking reaction with little pin-holes, although it was smallmolecule-based cross-linkable HTM. However, to solve the certain minor non-uniformity caused by pinholes with various sizes, a semi-interpenetrating network was formed with well-known polymeric HTM with high mobility [e.g., poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenyl amine), TFB, or poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine, poly-TPD]. As a result, we successfully fabricated red phosphorescent OLED showing an efficiency of about 16.7 cd/A and 12.4% (external quantum efficiency) if we applied PbV blended with 20% of TFB or poly-TPD. In particular, the efficiency and lifetime are significantly improved by 1.5 and 4.5 times, respectively, compared to those of the control device without using blended HTM.

No abstract

Correction for ‘An indenocarbazole-based host material for solution processable green phosphorescent organic light emitting diodes’ by Eun Young Park et al., RSC Adv., 2021, 11, 29115–29123. DOI: 10.1039/D1RA04855D.

A solution processed blue organic light emitting diodes was fabricated by using single component crosslinkable blue emitting materials. We successfully reduced a crosslinking temperaturedown to 135 °C by applying unique cyclic crosslinking units. From first blue emitting material, we obtained 7.86 cd/A of maximum current efficiency (CE) and 2.90 % of external quantum efficiency. And, we modified such material to give deeper blue OLED showing (0.16, 0.13) in CIE 1931 coordinate.