1 - Transparent, white OLED (OSRAM Opto Semiconductors). 2 - Measured and simulated mission pattern of a blue OLED. 3 - Thickness dependent efficiencies of a blue emitting OLED series.

Optical characterization and optimization of OLEDs

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Optics of organic LEDs

The quantitative optical description and general technical optimization of the upcoming, commercial light source organic LED require a profound knowledge of the active & passive optical properties of the system „OLED“.

 

Optical Characterization

  • Model free determination of thin film material dispersions n(λ)+ik(λ)
  • Measurement of layer thicknesses inside final OLED stacks
  • Measurement of polarized, angular & spectrally resolved emission pattern in air and substrate glass, respectively
  • Detailed optical modelling using in-house software („Radiating Slabs“)
  • Conclusion to properties of electrically pumped OLED emitting material

 

Emitter Properties

OLEDs comprising an adapted thin film stack (e.g. emitter – cathode – distance) enable to determine

  • internal electroluminescence spectrum,
  • emitter orientation distribution,
  • profile of the emission zone, and
  • quantum efficiency of excited state luminescence

by far-field radiation pattern measurement in conventional, electrically pumped operation and subsequent optical analysis.

 

References

M. Flämmich, N. Danz et al. in:

  • Appl. Opt. 48 (2009) 1507
  • Appl. Phys. Lett. 95 (2009) 263306
  • Org. Electron. 11 (2010) 1039

M.C. Gather, N. Danz et al. in:

  • Appl. Phys. Lett. 94 (2009) 263301