Red phosphorescent dopants

SCHEME 3.85 Chemical structure of some orange to red phosphorescent dopants. 

As the EL efficiency is limited by the poor phosphorescent dopant PtOEP, by using a good red phosphorescent iridium complex, Liu et al. demonstrated a very highly efficient PHOLED by applying a HBM [350], The device structure is ITO/NPD/CBP 6% Ir(piq-F)3/BCP/Alq3/Mg Ag. 

Abstract Mononuclear Ir(III)-polyimine complexes show outstanding luminescence properties, i.e., high intensities, lifetimes in the is time range, and emission wavelengths that can be tuned so as to cover a full range of visible colors, from blue to red. We discuss the approaches for the use of ligands that afford control on luminescence features. Emphasis is placed on subfamilies of cyclometalated complexes, whose recent enormous expansion is motivated by their potential for applications, including that as phosphorescent dopants in OLEDs fabrication. The interplay of the different excited states associated... 

A series of facial homoleptic cyclometalated iridium(III) complexes has been synthesized and their photophysical properties investigated. The MLCT emission of the complexes in toluene 298 K occurred at 558-652nm (To = 0.74-4.7 J,s). An OLED device that used [Ir(l-phenylisoquinolinato)3] as a phosphorescent dopant produced pure-red emission with very high efficiency. 

Polymer light-emitting devices (PLEDs) have attracted considerable interest because of their potential use in portable electronic devices. PLEDs have improved the performance of devices by increasing the device stability and efficiency. Chang and coworkers fabricated an efficient PLED using [Ir(acac)(dbq)2] as the phosphorescent dopant of a pvk matrix layer and bbpo as the electron transport material. Trapping of charge carriers at the [Ir(acac)(dbq)2] dopant sites dominates the EL of the device. This is the first PLED that emits red electrophosphorescence centered at 610 nm, exclusively from the dopant and an EL efficiency of 8.5 cdA (luminance 1287 cdm ) biased at 14.5 mAcm . ... 

Other work by Tsuboyama et al. reported a very highly efficient red PHOLED with power efficiency of 8.0 lm/W at 100 cd/m2 using Ir(piq)3 as a dopant [362], Most exciting, however, is the relatively recent demonstration of exceptional lifetimes for these materials in OLED devices where work from UDC has claimed a 14 cd/A red CIE (0.65, 0.35) with a lifetime of 25,000 h at 500 nit. Such performance promises much for phosphorescent red emitters in commercial devices and even higher efficiencies have been realized in systems that compromise the chromaticity toward the deep red with CIE (0.67, 0.33) and lifetimes >100,000 h at 500 cd/m2 [363],... 

Yellow and Red Dopants Phosphorescent Emitters Creating White Light Creating Polarized Light... 

PVK are critical in achieving high efficiency. While conjugated polymers, such as poly(fluorenes) and poly(phenylene-vinylenes), have been used extensively for fluorescence-based devices, they are not as useful for phosphorescence-based devices because they characteristically have low triplet energies. The triplet levels of most conjugated polymers are in the red to near-IR spectral region, and thus efficiently quench phosphorescence from dopants designed to emit in the visible part of the spectrum." ... 

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