Interference, OLED

FIGURE 6.25 Schematic diagram showing an OLED with a black cathode, the presence of an optical absorbing layer causes a destructive interference leading to a low reflection. 

External Quantum Efficiency Putting the interference effects and the photometric facet aside, the simpler way to determine the efficiency of an OLED is to measure how many photons are emitted outside the device, in the forward direction for each injected electron. This ratio rjext is called external quantum efficiency. ... 

Microcavity OLEDs fabricated on distributed Bragg reflectors (quarter wave stacks) [94]. Such OLEDs are fabricated on dielectric layers with significant dielectric contrast, so they narrow the emission spectrum by constructive interference. The narrow emission spectra also result in more efficient and more stable devices than regular OLEDs. The emission spectrum can be tailored to the specific sensor requirements (i.e., the absorption peak of the sensing element). 

Microcavity/Interference Effects in Weak Microcavity OLEDs.272... 

Therefore, emission properties of devices depend not only on intrinsic properties of emitting materials but are also often significantly modified by the optical structures of OLEDs. For instance, a typical OLED, which usually has one reflective metal cathode and one transparent indium tin oxide (ITO) anode on glass substrates (Figure 9.1), behaves like a weak microcavity. The device exhibits wide-angle interference between directly emitting radiation and reflected radiation, as... 

Illustration of optical phenomena in OLEDs (a) wide-angle interference in noncavity (weak microcavity) OLED (b) wide-angle and multiple-beam interference in strong microcavity OLEDs. (From Wu, C.-C. et al., /. Display Technol, 1,248,2005. With permission.)... 

Augustin A, Spenlehauer C, Dumond H et al. PARP-3 localizes preferentially to the dai ter centri-ole and interferes with the Gl/S cell cycle progression. J Cell Sci 2003 116(Pt 8) 1331-62. 

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