Yao-Shan Wu

Highly efficient deep blue organic electroluminescent device based on 1-methyl-9,10-di(1-naphthyl)anthracene

The author have developed 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN) as an effective wide band gap host material for Forster energy transfer to the unsymmetrical mono(styryl)amine deep blue fluorescent dopant (BD-1). This guest/host emitting system, at the optimal doping concentration of 3%, can also increase the probability of carrier recombination near the hole-transport/emitting layer interface for the blue organic light emitting device which produces electroluminescence efficiencies of 3.3cd∕A and 1.3lm∕W and a deep blue CIEx,y color coordinates of (0.15, 0.13) that are 50% better than those of the traditional β,β-isomeric host (MADN) with the same dopant.

Highly efficient yellow and white organic electroluminescent devices doped with 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene

We describe the applications of a sterically-hindered yellow dopant, 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (TBRb) which, when compared to 5,6,11,12-tetraphenylnaphthacene (Rb) in either tris(8-hydroxyquinolinato)aluminum or 1,4-bis[N-(1-naphthyl)-N′-phenylamino]−4,4′ diamine (NPB) as host emitter, shows a 50%–34% increase in luminance efficiency over that of Rb device without significantly affecting its color. In addition, we have incorporated the TBRb doped yellow NPB emitter into the two-element white organic light-emitting diodes based on p-bis(p-N,N-di-phenyl-aminostyryl)benzene doped 2-methyl-9,10-di(2-naphthyl) anthracene sky-blue emitter which improved the luminance efficiency by 44% over that of Rb to 12.8cd∕A and 4.3lm∕W at 20mA∕cm2 with CIEx,y=[0.31,0.38].

Efficient deep blue emitters for organic electroluminescent devices

Highly efficient deep blue organic light emitting devices have been fabricated with a 4-(styryl)biphenyl-core based fluorescent dopant (SK-1) in the wide band gap 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN) host system which achieved an electroluminescence efficiency of 5.0cd∕A and an external quantum efficiency of 4.2% at 20mA∕cm2 with a saturated blue Commission Internationale de l’Eclairage coordinates of (0.15, 0.14) and a half-decay lifetime of 8000h at an initial brightness of 100cd∕m2. The current efficiency and electroluminescent color of SK-1 doped devices have been shown to be essentially immune to drive current density.

Phosphorescence of red Os(fptz)(2)(PPh2Me)(2) doped organic light-emitting devices with n and p hosts

We have applied a stericly-hindered red phosphorescent dopant Os(fptz)2(PPh2Me)2 [fptz=3-trifluoromethyl-5-(2-pyridyl)-1,2,4-triazole, PPh2Me=phosphine ligand] in p-type 4,4′-N,N′-dicarbazole-biphenyl or n-type bis(2-methyl-8-quinolinolato)(p-phenylphenolato) aluminum host and found that the latter produced higher luminance efficiency at lower doping concentration. We present a model to rationalize this phenomenon in which the n-type host impedes hole transport, which leads to narrower recombination zone near the hole transport layer/emission layer interface than the p-type host, hence, more effective recombination.

P-115: Efficient Blue Organic Electroluminescent Devices Based on a Stable Blue Host Material

We have successfully synthesized a new blue host material, 2-methyl-9,10-di(2-napthyl)anthracene (MADN) which is highly stable in thin-film morphology comparing to the archetypical 9,10-di(2-napthyl)anthracene (ADN). When doped with 2,5,8,11-tetra(t-butyl)perylene (TBP) as blue emitter in organic light emitting device (OLED), MADN shows an improved EL efficiency of 4.4 cd/A and 2.2 lm/W at 20 mA/cm2 and 6.3 V with a CIEx, y coordinate of (0.14, 0.20). The blue device is stable with an extrapolated t1/2 ∼5000 h at an initial brightness of 880 cd/m2.

64.2: Highly Efficient Deep Blue Electroluminescent Devices

A new deep blue dopant (SK-1) based on “linked” stilbene moiety has been designed and synthesized. When doped in the stable blue host material, 2-methyl-9,10-di(1-naphthyl)anthracene (α,α-MADN), the SK-1 doped blue device achieved a luminance efficiency of 5.0 cd/A with corresponding CIEx,y of (0.14, 0.14) at 20 mA/cm2 and an external quantum efficiency of 4.2%. The performance of SK-1 doped device performance under high/low drive current density remains stable for the needs of full color OLED application.