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Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Editor: Joseph N. Mait
  • Vol. 48, Iss. 8 — Mar. 10, 2009
  • pp: 1507–1513

Dispersion-model-free determination of optical constants: application to materials for organic thin film devices

Michael Flämmich, Norbert Danz, Dirk Michaelis, Andreas Bräuer, Malte C. Gather, Jonas H.-W. M. Kremer, and Klaus Meerholz  »View Author Affiliations


Applied Optics, Vol. 48, Issue 8, pp. 1507-1513 (2009)
http://dx.doi.org/10.1364/AO.48.001507


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Abstract

We describe a method to determine the refractive index and extinction coefficient of thin film materials without prior knowledge of the film thickness and without the assumption of a dispersion model. A straightforward back calculation to the optical parameters can be performed starting from simple measurements of reflection and transmission spectra of a 100 250 nm thick supported film. The exact film thickness is found simultaneously by fulfilling the intrinsic demand of continuity of the refractive index as a function of wavelength. If both the layer and the substrate are homogeneous and isotropic media with plane and parallel interfaces, effects like surface roughness, scattering, or thickness inhomogenei ties can be neglected. Then, the accuracy of the measurement is approximately 10 2 and 10 3 for the refractive index and the extinction coefficient, respectively. The error of the thin film thickness determination is well below 1 nm . Thus this technique is well suited to determine the input parameters for optical simulations of organic thin film devices, such as organic light-emitting diodes (OLEDs) or organic photovoltaic (OPV) cells. We apply the method to the electroluminescent polymer poly(2,5-dioctyl-p-phenylene vinylene) (PDO-PPV) and show its applicability by comparing the measured and calculated reflection and transmission spectra of OLED stacks with up to five layers.

© 2009 Optical Society of America

OCIS Codes
(160.4760) Materials : Optical properties
(160.4890) Materials : Organic materials
(230.0250) Optical devices : Optoelectronics
(250.2080) Optoelectronics : Polymer active devices
(310.6860) Thin films : Thin films, optical properties
(310.6845) Thin films : Thin film devices and applications

ToC Category:
Materials

History
Original Manuscript: November 5, 2008
Revised Manuscript: February 5, 2009
Manuscript Accepted: February 5, 2009
Published: March 4, 2009

Citation
Michael Flämmich, Norbert Danz, Dirk Michaelis, Andreas Bräuer, Malte C. Gather, Jonas H.-W. M. Kremer, and Klaus Meerholz, "Dispersion-model-free determination of optical constants: application to materials for organic thin film devices," Appl. Opt. 48, 1507-1513 (2009)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-48-8-1507


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