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Substituent position engineering of diphenylquinoline-based Ir(iii) complexes for efficient orange and white PhOLEDs with high color stability/low efficiency roll-off using a solution-processed emission layer.
- Source :
- Journal of Materials Chemistry C; 1/7/2016, Vol. 4 Issue 1, p113-120, 8p
- Publication Year :
- 2016
-
Abstract
- Three new heteroleptic Ir(iii) complexes o-LIrpic, m-LIrpic, and p-LIrpic (L = CF<subscript>3</subscript>DPQ) consisting of 2,4-diphenylquinoline (DPQ) with a –CF<subscript>3</subscript> group at ortho (o)/meta (m)/para (p) positions of the metalated phenyl ring, respectively, as the main ligands were synthesized and used as emitters in phosphorescent organic light-emitting diodes (PhOLEDs). We realized that –CF<subscript>3</subscript> position extremely affects the crucial photophysical and electronic properties such as emission color, photoluminescence quantum yield (PLQY) and energy levels of these Ir(iii) complexes resulting in –CF<subscript>3</subscript> position-dependent performance of their PhOLEDs. To verify the effect of –CF<subscript>3</subscript> group position on device performance, three other Ir(iii) complexes o-LIrtmd, m-LIrtmd, and p-LIrtmd were synthesized using the same main ligands but a different ancillary ligand. In the two series of Ir(iii) complexes, the devices with m-CF<subscript>3</subscript> based complexes are outstanding in performance compared to o- or p-CF<subscript>3</subscript> based ones due to the enhanced PLQY and well suppressed non-radiative deactivations by m-substitution. Finally, the single emission layer solution-processed orange and two-component white PhOLEDs fabricated using m-LIrpic as orange emitter achieved the maximum external quantum efficiency of 17.1% (43.9 cd A<superscript>−1</superscript>) and 21.1% (48.8 cd A<superscript>−1</superscript>), respectively, with highly stable color coordinates and low efficiency roll-off. This is the highest efficiency reported to date for solution-processed orange PhOLEDs using a small molecular host with easily accessible emitter. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20507526
- Volume :
- 4
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Journal of Materials Chemistry C
- Publication Type :
- Academic Journal
- Accession number :
- 111818777
- Full Text :
- https://doi.org/10.1039/c5tc03004h