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 language | English |
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Article number | 030604 |
Journal | Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics |
Volume | 32 |
Issue number | 3 |
DOIs | |
Publication status | Published - May 1 2014 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Instrumentation
- Process Chemistry and Technology
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering
- Materials Chemistry