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Waveguiding, Modes, Organic LEDs

  1. Nov 5, 2008 #1
    Hi everyone,

    I was wondering if someone could please explain to me the concept of
    waveguiding, coupling/coupled, and guiding mode.

    Here is an application of these terms:

    The photons emitted in the active region of OLEDs are
    coupled into three types of modes: direct transmission into
    the air, the glass total internal reflection mode, and the highindex
    ~ITO/organic! guided mode. Assuming Lambertian
    light sources, the fractions of energy in the three modes have
    been estimated as 0.2, 0.3, and 0.5, respectively.2 A number
    of methods have been suggested for increasing the output
    coupling efficiency. For example, random textures or ordered
    microlens arrays have been employed on the top surface of
    the glass substrate in order to minimize total internal
    reflection.3,4 The thickness of the ITO layer has also been
    controlled in order to reduce the energy in the high-index
    layer.5 An integrated classical and quantum-mechanical weak
    microcavity theory has been proposed in order to calculate
    the efficiencies of each mode for OLED layered structure.6

    I dont really understand HOW a photonic crystal helps "waveguide" these modes OUT of the OLED? I appreciate your help. Thanks!

    Source: pbg.kaist.ac.kr/pdf_text/yjlee03APL.pdf
  2. jcsd
  3. Nov 6, 2008 #2
    ^ Bump ^

    Please, any help is appreciated. I have a presentation due in a couple of days.

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