Crosslinkable hole-transporting small molecule as a mixed host for efficient solution-processed red organic light emitting diodes

• Published in: Thin solid films 2018-08, Vol.660, p.956-960
• Main Authors: Dubey, Deepak Kumar, Yadav, Rohit Ashok Kumar, Tavgeniene, D., Grigalevicius, Saulius, Jou, Jwo-Huei
• Format: Article
• Language: English
• Subjects: Co-host; Hole transporting material; Red OLED; Solution process; Thermal crosslinking
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2018.01.047

The fabrication of multilayer organic light-emitting diodes through solution processing presents numerous challenges, primarily concerning dissolution of the first layer during deposition of a second layer. Here, we demonstrate a highly efficient solution processed red organic light emitting diode utilizing an electron confining cross linkable small molecule, 9,9′-bis(4-vinylphenylmethylen)[3,3′]bi-carbazole, as a hole transporting and co-host material. Compared with the corresponding single host device, the luminance of the mixed host device is enhanced from 8351 cd m−2 to 15,200 cd m−2, an increment of 82%, in addition, power efficiency and current efficiency also show an increment of 25% and 20% at 100 cd m−2, respectively. Results show that use of the crosslinking material makes the hole injecting, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), layer more intact during the deposition of the emissive layer which improves the film quality and hence device brightness. The enhanced charge carrier balance and broadened exciton recombination zone due to the mixed host contribute to the improvement of efficiency and efficiency roll-off. •Solution-processed organic light emitting diodes•Thermally-activated, crosslinkable, electron-confining, hole-transporting material as a co-host•Annealing improves the thin-film integrity of deposited layers.•Balance charge carrier and broadened exciton recombination zone due to the co-host