Efficient organic light-emitting devices using an iridium complex as a phosphorescent host and a platinum complex as a red phosphorescent guest

Abstract

We demonstrated efficient organic light-emitting devices (OLEDs) using a phosphorescent host/guest system consisting of bis(2-phenylpyridinato-N,C2′)iridium(acetylacetonate) [(ppy)2Ir(acac)] as a host and a platinum complex (Pt-SA-1) as a guest. The OLED using (ppy)2Ir(acac) film doped with Pt-SA-1 (1wt%) showed an ideal red emission via efficient energy transfer from the host to the guest. The external quantum efficiency of the device was as high as 8.3%. The driving voltage was significantly reduced compared with a device using a conventional host of 4,4′-di(carbazole-9-yl)biphenyl, which resulted from the enhancement of the hole injection from the hole-transport layer to the host.

Phosphorescent Iridium(III) Complexes with Nonconjugated Cyclometalated Ligands

“…8-10 wt %) to ensure effective energy transfer. [20] Thus, in using the phosphorescent organometallic complexes as hosts, the emitting dopant concentration can be substantially reduced (e.g. 2 wt % in the present case).…”

Efficient and low-voltage phosphorescent organic light-emitting devices based on blue iridium complex host

“…For example, Tsuzuki et al [13] reported an efficient red PHOLED, which could be driven at a low voltage of 4.4 V at 100 cd/m 2 ), with phosphorescent material bis(2-phenyl-pyridinato-N,C 2 ' ) iridium(acetylacetonate)[(ppy) 2 Ir(acac)] as the host and tris(1-phenylisoquinolinolato-C 2 ,N)iridium(III) as the guest. Meanwhile, they doped a platinum complex [2,2'-1,2-phenylenebis(nitrilomethylidyne) bis 4,6-di-tertbutylphenolate-N,N',O,O'] platinum(II) in the phosphorescent material (ppy) 2 Ir(acac) and obtained a maximum external quantum efficiency of 8.3% and a maximum current efficiency (η c,max ) of 4.9 cd/A at the same time [16] .…”

“…In order to solve the problems above, phosphorescent materials are expected to play the part of host, which is beneficial to the enhancement of carrier injection from the carrier transport layer to the host. There have been only a few reports on phosphorescent OLEDs based on phosphorescent host materials [5,[11][12][13][14][15][16] , and almost all of the reports have focused on monochromatic red OLEDs. For example, Tsuzuki et al [13] reported an efficient red PHOLED, which could be driven at a low voltage of 4.4 V at 100 cd/m 2 ), with phosphorescent material bis(2-phenyl-pyridinato-N,C 2 ' ) iridium(acetylacetonate)[(ppy) 2 Ir(acac)] as the host and tris(1-phenylisoquinolinolato-C 2 ,N)iridium(III) as the guest.…”

[Pt(topy)(Htopy)(ONO2)] complex (Htopy = 2‐p‐tolylpyridine) and its analogs: 195Pt NMR spectra and fabrication of light‐emitting devices

“…Examples include a red-emitting device containing (Pt{2,2-[1,2-phenylenebis(nitrilomethylidyne)]bis(4,6-di-tert-butylphenolate)]}, which showed Commission Internationale de L'Eclairage (CIE) color coordinates of (0.68, 0.32) and λ max of 645 nm; [6] an orangeemitting device containing {Pt[(9,9-diethyl-7-pyridin-2-ylfluoren-2-yl)diphenylamine](acac)}, which has CIE coordinates (0.55, 0.45) and λ max 572 nm; [11] a white-emitting device containing {Pt[N, Nbis(salicylidene)-1,2-ethylenediamine]}, with CIE coordinates (0.33, 0.35) and λ max 448, 552 nm; [8] and a green-emitting device containing [Pt(pentafluorophenyl) 2 (4,7-diphenylphenanthroline)], with CIE coordinates (0.329, 0.551) and λ max 519 nm. [7] As 2a and 2b show luminescence at short wavelengths and strong luminescence intensity, they are suitable candidates for emitters in high-efficiency OLEDs.…”