Luminance, coordination polymers

Spiro-FPAl/TPBI/Bphen Cs/Al. A very low operating voltage of 3.4 V at luminance of 1000 cd/m2 was obtained, which is the lowest value reported for either small-molecule or polymer blue electroluminescent devices. Pure blue color with CIE coordinates (0.14, 0.14) have been measured with very high current (4.5 cd/A) and quantum efficiencies (3.0% at 100 cd/m2 at 3.15 V) [245]. In another paper, Spiro-FPA2 (126) was used as a host material with an OLED device structure of ITO/CuPc/NPD/spiro-FPA2 l%TBP/Alq3/LiF that produces a high luminescent efficiency of 4.9 cd/A [246]. 

Due to the large band gap and high triplet energy level of the poly(3, 6-dibenzosilole) 5, the copolymer is an excellent host for the fabrication of blue polymer phosphorescent light-emitting diodes. A high external quantum efficiency (t/el) of 4.8% and a luminance efficiency of 7.2 cd/A at 644 cd/m2 have been achieved for blue phosphorescence devices (emission peak (AEL) at 462 nm, CIE coordinates x = 0.15,y = 0.26). The performances of the devices are much better than those reported for blue phosphorescent devices with poly(A--viny 1 cabarzo 1 e) (PVK) as the host.32... 

The nature of Dexter triplet energy transfer between bonded systems of a red phosphorescent Ir + complex and a conjugated polymer, polyfluorene, has been investigated in electrophosphorescence OLEDs . Red-emitting phosphorescence has been described based on the [Ir(btp)2(acac)j fragment attached either directly (spacerless) or through a —(CH2)8— chain (octamethylene-tethered) at the 9-position of a 9-octylfluorene host. Xu and coworkers reported that an efficient red EP with CIE chromaticity coordinates X = 0.69, y = 0.29, independent on current density, was obtained from [Ir(acac)(btfmp)2] doped devices. The EL spectrum has a maximum at 648 nm. A maximum external quantum efficiency of 9.6%, at current density of 0.125 mAcm, and a maximum luminance of 4200 cdm , at 7 = 552 mAcm , have been obtained. 

On the other hand, Scherf and coworkers used N,N-bis(4-methylphenyl)-N-phenylamine as the end-capper to yield the polymer 16 (end-capper concentration 3 mol%) its single-layer device (ITO/PEDOT PSS/16/Ca/Al) exhibited maximum luminance of 1600cdm 2 and efficiency of 1.1 cdA-1, with CIE coordinates (0.15, 0.08) at 8.5 V [29]. This efficiency is higher than that of non-end-capped polymer 3 (that is, bromine exists at each chain end) by one order of magnitude and was attributed to an efficient hole trapping at the... 

Introducing red-light emitting Ir(III) complex and BT into the main-chain of polyfluorene (polymer 23) can realize white-light emission. A WPLED with a structure of ITO/PEDOT PSS/PVK/polymer 23/CsF/Al showed a maximum external quantum efficiency of 3.7% and the maximum luminous efficiency of 3.9 cd/A at the current density of 1.6 mA/cm2 with the CIE coordinates of (0.33, 0.34). The maximum luminance of 4180 cd/m2 is achieved at the current density of 268 mA/cm2 with the CIE coordinates of (0.31,... 

PSS = poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) and is a conducting polymer. The emissive layer also contains small amounts of an ionic liquid (e.g. l-butyl-3-methylrmidazolium hexalluoridophosphate, see Sectitm 9.12) which is added to reduce the time to reach the maximum luminance of the device, (b) An example of a coordination complex used in EECs. (c) The use of face-to-face ir-stacking to stabilize the ground and excited states of the complex in a LEC. 

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