Photo-crosslinking of pendent uracil units provides supramolecular hole injection/transport conducting polymers for highly efficient light-emitting diodes

Hsi Kang Shih, Yi Han Chen, Yu Lin Chu, Chih Chia Cheng, Feng Chih Chang, Chaoyuan Zhu*, Shiao Wei Kuo

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

A new process for modifying a polymeric material for use as a hole injection transport layer in organic light-emitting diodes has been studied, which is through 2π + 2π photodimerization of a DNA-mimetic π-conjugated poly(triphenylamine-carbazole) presenting pendent uracil groups (PTC-U) under 1 h of UV irradiation. Multilayer florescence OLED (Organic light-emitting diodes) device with the PTC-U-1hr as a hole injection/transport layer (ITO (Indium tin oxide)/HITL (hole-injection/transport layer) (15 nm)/N,N'-di(1-naphthyl)- N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) (15 nm)/Tris-(8-hydroxyquinoline) aluminum (Alq3) (60 nm)/LiF (1 nm)/Al (100 nm)) is fabricated, a remarkable improvement in performance (Qmax (external quantum efficiency) = 2.65%, Bmax (maximum brightness) = 56,704 cd/m2, and LE (luminance efficiency)max = 8.9 cd/A) relative to the control PTC-U (Qmax = 2.40%, Bmax = 40,490 cd/m2, and LEmax = 8.0 cd/A). Multilayer phosphorescence OLED device with the PTC-U-1hr as a hole injection/transport layer (ITO/HITL (15 nm)/Ir(ppy)3:PVK (40 nm)/BCP (10nm)/Alq3 (40 nm)/LiF (1 nm)/Al (100 nm)) is fabricated by successive spin-coating processes, a remarkable improvement in performance (Qmax = 9.68%, Bmax = 41,466 cd/m2, and LEmax = 36.6 cd/A) relative to the control PTC-U (Qmax = 8.35%, Bmax = 34,978 cd/m2, and LEmax = 30.8 cd/A) and the commercial product (poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) PEDOT:PSS (Qmax = 4.29%, Bmax = 15,678 cd/m2, and LEmax = 16.2 cd/A) has been achieved.

Original languageEnglish
Pages (from-to)804-818
Number of pages15
JournalPolymers
Volume7
Issue number5
DOIs
StatePublished - 1 Jan 2015

Keywords

  • Hole injection/transport
  • OLED
  • Phosphorescence
  • Photo-crosslinking
  • Uracil

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