Phosphorescent Osmium (II) complexes and uses thereof

Abstract

There is disclosed herein phosphorescent compounds, uses thereof, and devices including organic light emitting diode (OLEDs) including such compounds. Compounds of interest include: wherein A is Os or Ru The anionic chelating chromophores NˆN, which are formed by connecting one pentagonal ring structure containing at least two nitrogen atoms to a hexagonal pyridine type of fragment via a direct carbon-carbon linkage. L is a neutral donor ligand; the typical example includes carbonyl, pyridine, phosphine, arsine and isocyanide; two neutral L's can also combine to produce the so-called chelating ligand such as 2,2′-bipyridine, 1,10-phenanthroline and N-heterocyclic carbene (NHC) ligand, or bidentate phosphorous ligands such as 1,2-bis(diphenylphosphino)ethane, 1,2-bis(diphenylphosphino)benzene. L can occupy either cis or trans orientation. When L occupies the trans position, the preferred structure contains both the hexagonal fragment of NˆN as well as its pentagonal fragment located at the trans position respect to their counterparts of the second NˆN chromophore. When L occupies the cis position, the preferred structure consists of the pentagonal unit of NˆN chromophores residing opposite to the L. X,1 X2 and X3 independently are C or N; when X2 is N, R1 is omitted, when X3 is N, R2 is omitted, R1 is H, C1-C8 alkyl, C1-C8 substituted phenyl or C1-C4 perfluoroalkyl, R2 is H, F or cyano substituent, X4 is either C or N; X4 may locate at any position of the hexagonal ring, when X4 is N and R3 and R4 are not linked to X4, R3 is H, methyl or C1-C3 small alkyl, R4 is H, methyl or C1-C3 small alkyl, or R3 and R4 together form an additional conjugated unit with structure

Description

FIELD OF THE INVENTION [0001] The invention relates to phosphorescent compounds and uses thereof. CROSS-REFERENCE TO RELATED APPLICATIONS [0002] This application is a continuation of U.S. Ser. No. 10 / 981,755 filed on Nov. 5, 2004 which is incorporated herein by reference. BACKGROUND [0003] It has long been felt that a technically viable emissive display technology could compete with the currently dominating technology of liquid crystal displays (LCDs), and OLEDs are presently considered well placed to do so. While the technology of LCDs has various limitations such as low efficiency, poor viewing angles, slow switching speed and narrow temperature ranges, the main advantages of OLEDs are full color, high efficiency, large viewing angles, high switching speed, and low operational temperature. Therefore, organic light emitting diodes (OLEDs) and polymer light emitting diodes (PLEDs) have attracted a tremendous amount of research interests from both academia and industry in the past de...

AI Technical Summary

Problems solved by technology

While the technology of LCDs has various limitations such as low efficiency, poor viewing angles, slow switching speed and narrow temperature ranges, the main advantages of OLEDs are full color, high efficiency, large viewing angles, high switching speed, and low operational temperature.

While some materials meet or exceed some of the requirements for commercial displays, none are believed to meet them all.

Efficient and stable red and blue emitters are especially lacking.

The design and synthesis of red emitting complexes is intrinsically difficult because their luminescence quantum yield tends to their ionic nature observed in the traditional design involving Os(II) complexes such as [Os(bpy)3][PF6]2, where bpy=2,2′-bipyridine; [Carlson, B. et al., J. Am. Chem. Soc.

The positively charged Os(II) fragments and their counter anions may undergo significant drifting under high electric field during device operation towards the cathode and the anode, respectively, leading to instability in device performance and a relatively long response time.

Images