Accurate measurement of dopant concentration in organic light-emitting diodes by combining high-performance liquid chromatography and TOF-SIMS

Hiroshi Fujimoto, Tomohiko Edura, Takuya Miyayama, Noriaki Sanada, Chihaya Adachi

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The authors report the use of high-performance liquid chromatography (HPLC) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) utilizing a gas cluster ion beam to accurately measure the dopant concentration and its depth profile in organic thin films used for organic light-emitting diodes. The total dopant concentrations estimated by HPLC for films of 4,4'-bis(carbazol-9-yl)biphenyl (CBP) doped with tris(2-phenylpyridinato)iridium(III) (Ir(ppy)3) are consistent with those measured by quartz crystal microbalances (QCMs) during the deposition. Concentrations measured for Ir(ppy)3:CBP films by HPLC and TOF-SIMS show a nearly linear relationship in the range of 1-8 wt. %. At concentrations higher than 8 wt. %, TOF-SIMS values significantly deviate because of the matrix effect. The depth profile of the dopant concentration measured by TOF-SIMS was in good agreement with that measured by QCMs during film deposition for concentrations below 8 wt. %. These methods are especially useful for comparing the dopant concentration of films deposited in different batches and equipment.

Original languageEnglish
Article number030604
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Volume32
Issue number3
DOIs
Publication statusPublished - May 1 2014

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liquid chromatography
High performance liquid chromatography
Organic light emitting diodes (OLED)
Secondary ion mass spectrometry
secondary ion mass spectrometry
light emitting diodes
Doping (additives)
Quartz crystal microbalances
Iridium
quartz crystals
microbalances
Ion beams
Gases
Thin films
profiles
iridium
ion beams
matrices
thin films
diphenyl

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this

Accurate measurement of dopant concentration in organic light-emitting diodes by combining high-performance liquid chromatography and TOF-SIMS. / Fujimoto, Hiroshi; Edura, Tomohiko; Miyayama, Takuya; Sanada, Noriaki; Adachi, Chihaya.

In: Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics, Vol. 32, No. 3, 030604, 01.05.2014.

Research output: Contribution to journalArticle

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