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ABSTRACT
A new iridium-based cyclometalated complex, namely bis (2-phenylpyridine–C2, N′) iridium (III) picolinate [(ppy)2Ir(pic)] is synthesized and investigated as electrophosphorescent dopant in polymer-based organic light-emitting diodes. The photoluminescence emission from this complex is observed at 501 nm, with a shoulder at 526 nm. Poly(N-vinylcarbazole) (PVK) is used as host polymer and single-layer devices of PVK doped with (ppy)2Ir(pic) complex are fabricated. Photoluminescence (PL) spectra of PVK films doped with different concentration of iridium complex were measured to study the possible energy transfer occurring between PVK to iridium complex. A predominant blue to a completely green shifted emission is observed when the doping concentration was increased from 0% to 5 wt%. Optical and atomic force microscopic images of the doped films indicate a smooth film formation when spin coated with chlorobenzene as a solvent as compared to chloroform. Electroluminescence spectra of ITO/PEDOT:PSS/PVK:(ppy)2Ir(pic)/Al device resembles that of the PL spectra with emission at 507 nm and Commission Internationale de l'Eclairage (CIE) coordinates (0.29, 0.57).
Keywords:
- Current–voltage characteristics
- Electroluminescence (EL)
- Electrophosphorescence
- Energy transfer
- Film morphology
- Highest occupied molecular level (HOMO)
- Lowest occupied molecular level (LUMO)
- Luminance
- Metal-organic complex
- Organic light-emitting diodes (OLED)
- Photoluminescence (PL)
- Singlet and triplet states
- Solvent effect
- Spin-orbit coupling