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Nanoparticle-loaded encapsulation materials for light-emitting diode applications

Published online by Cambridge University Press:  01 February 2011

Frank Wilhelm Mont ,
H. Luo ,
M. F. Schubert ,
J. K. Kim ,
E. F. Schubert  and
R. W. Siegel
Frank Wilhelm Mont
Affiliation:
montf@rpi.edu, Rensselaer Polytechnic Institute, Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, 110 8th street, Troy, NY, 12180, United States, 518-276-8133
H. Luo
Affiliation:
xiy@rpi.edu, Rensselaer Polytechnic Institute, Future Chips Constellation, Department of Physics, Applied Physics, and Astronomy, Troy, NY, 12180, United States
M. F. Schubert
Affiliation:
schubm@rpi.edu, Rensselaer Polytechnic Institute, Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Troy, NY, 12180, United States
J. K. Kim
Affiliation:
kimj4@rpi.edu, Rensselaer Polytechnic Institute, Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Troy, NY, 12180, United States
E. F. Schubert
Affiliation:
EFschubert@rip.edu, Rensselaer Polytechnic Institute, Future Chips Constellation, Department of Electrical, Computer, and Systems Engineering, Troy, NY, 12180, United States
R. W. Siegel
Affiliation:
rwsiegel@rpi.edu, Rensselaer Polytechnic Institute, Department of Materials Science and Engineering and Rensselaer Nanotechnology Center, Troy, NY, 12180, United States
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Abstract

Nanoparticle-loaded encapsulants provide unique optical and material properties for the enhancement of light extraction efficiency in light-emitting diodes (LEDs). We report on the uniform dispersion of TiO2 nanoparticles with average diameter of 40 nm in epoxy, and the demonstration of a refractive index (n)of 1.68 at 400 nm wavelength, higher than that of pure epoxy (n = 1.53). It is found that proper chemical surfactants and nanoparticle preparation are critical to eliminate agglomeration of nanoparticles. Theoretical analysis of optical scattering in nanoparticle-loaded encapsulation materials reveals that although the size and loading factor of nanoparticles greatly influence scattering, specular transparency of the encapsulant film occurs if the thicknesses of the films are kept below the optical scattering length. Furthermore, the encapsulants benefit from an optimized scattering coefficient as demonstrated by three-dimensional ray-tracing simulations showing light extraction efficiency enhancements greater than 50%.

Keywords

optical propertiesopticalpackaging
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 955: Symposium I – Advances in III-V Nitride Semiconductor Materials and Devices , 2006 , 0955-I13-02
Copyright
Copyright © Materials Research Society 2007

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References

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