A high‐efficacy white OLED device is reported. At 1,000 cd/m2, the device showed an efficacy of 56 lm/W. The color at (0.387, 0.389) was within the Energy Star tolerance quadrangle; the CRI at 83.6 exceeded the requirements. The device had a tandem hybrid architecture comprising a fluorescent blue‐emitting unit and a phosphorescent yellow‐red‐emitting unit. It also had an internal extraction enhancement structure that greatly enhanced the light extraction efficiency.
An all‐fluorescent white OLED device with 14.5% external quantum efficiency and 31.2 lm/W efficacy has been demonstrated. The color coordinate at (0.387, 0.381) falls well within the DOE Energy Star tolerance quadrangle for 4000K CCT. The T50 lifetime is projected to be over 10,000 h at an initial brightness of 1,000 cd/m2. The performance is achieved through the use of improved OLED materials, improved architecture, as well as a light extraction structure that more than doubles the light extraction efficiency.
An analytical model has been constructed t o predict the birefringence level in an injuection-molded disk with direct application to optical disk substrates. The model incorporates simplified analyses for the flow in a center-gated cavity during the filling stage, the heat transfer during the cooling stage, and the stress relaxation following the cessation of flow at the end of the filling stage of the injection-molding cycle. The stress relaxation process is analyzed with the integral constitutive equation of Wagner and the residual stresses are converted to retardation via the stress-optical law. Predictions of normal retardation profiles are in line with experimental data and the general effects of melt temperature, mold temperature, and injection speed are closely captured by the model. By contrast, the observed transverse retardation is not in accord with the predicted response. This discrepancy is attributed to the fact that the transverse retardation is induced by cooling stresses and thus cannot be explained in terms of a flow stress mechanism employed in the present analysis.
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