General application of blade coating to small-molecule hosts for organic light-emitting diode

Hao Wen Chang, Yi Ting Lee, Mei Rurng Tseng, Meng Hao Jang, Han Cheng Yeh, Fang Tsai Luo, Hsin-Fei Meng*, Chin Ti Chen, Yun Chi, Yong Qiu, Lian Duan, Hao Wu Lin, Sheng Fu Horng, Hsiao-Wen Zan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Blade coating is applied to multi-layer phosphorescent OLED with five small-molecule hosts for the emission layer, including bis[3,5-di (9H-carbazol-9-yl)phenyl]diphenylsilane (SimCP2), 2,6-bis(3-(9H-carbazol-9-yl) phenyl) pyridine (26DCzPPy), 4,4′,4″-tris-(N-carbazolyl)- triphenylamine (TCTA), 9,9-bis[4-(3,6-di-tert-butylcarbazol-9-yl)phenyl]fluorene (TBCPF), and 2,7-bis(diphenylphosphoryl)-9,9′-spirobi[fluorene] (SPPO13). In general, blade coating gives low surface roughness around 0.2 nm without phase separation of the emitter and the host. In the large area of 2 cm by 3 cm the film thickness distribution is within 10% and uniform light-emission is achieved. 1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7) is added to tune the electron transport. Among all the hosts, 26DCzPPy and SimCP2 have by far the best electron-hole balance and consequently show the highest efficiency. For SimCP2, the maximal efficiency is 15.8 cd/A for blue and 24.2 cd/A for white emission. The order of efficiencies for the hosts is found to be quite different from the order in vacuum evaporation for the same device structures.

Original languageEnglish
Pages (from-to)99-109
Number of pages11
JournalSynthetic Metals
Volume196
DOIs
StatePublished - 1 Jan 2014

Keywords

  • Blade coating
  • Organic light-emitting diodes
  • Phosphorescence
  • Solution process

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