N∧C∧N-Coordinated Platinum(II) Complexes as Phosphorescent Emitters in High-Performance Organic Light-Emitting Devices

• Published in: Advanced functional materials 2007-01, Vol.17 (2), p.285-289
• Main Authors: Cocchi, M., Virgili, D., Fattori, V., Rochester, D. L., Williams, J. A. G.
• Format: Article
• Language: English
• Subjects: Electroluminescence; Light emitting diodes; Light emitting diodes, organic (OLEDs); organic (OLEDs); Platinum; Quantum efficiency
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200600167

A series of terdentate cyclometallated PtII complexes with remarkable luminescence properties are used as new phosphorescence‐emitting dopants in a blended host matrix as the emitting layer, resulting in very high electroluminescence efficiencies. Because of the high phosphorescence quantum yields of these Pt complexes and the efficient energy transfer from both singlet and triplet excited states of the host to the emitting guest, external electroluminescence quantum efficiencies as high as 4–16 % photons per carrier and luminous efficiencies of 15–40 cd A–1 are achieved. Moreover, these high efficiency values were maintained over a four‐decade current intensity span with no significant roll‐off. Tuning of the electroluminescence spectra from the yellow to the green‐bluish region of the chromaticity diagram is obtained simply by changing the substituents at the central 5‐position of the cyclometallating ligand. External electroluminescence quantum efficiencies of 4–16 % and luminous efficiencies of 15–40 cd A–1 maintained over a four‐decade current intensity span have been achieved with terdentate PtII complexes. Color tuning was achieved by ligand substitution, resulting in emission in the yellow, deep green, and blue range (see figure).