Abstract
Compared to the OLED with planar substrate, the
luminous current efficiency and luminous power
efficiency of the device are shown 25% and 36%
enhancement, respectively, by attaching the microlens
array film (MAF) having a fill factor of 0.788 and a
height ratio of 0.46. Both the luminous current
efficiency and luminous power efficiency of the organic
light-emitting device (OLED) increased monotonically
with increasing the fill factor of MAFs, regardless of
their arrangements. However, the curve-fitting equation
of the luminous power efficiency has a negative
second-order term, which shows a saturation phenomenon.
Based on the experimentally verified configuration,
simulation showed that the luminous current and power
efficiencies also increase along with increasing height
ratio and they were found to have more pronounced
saturation phenomena. As for the spectral
characteristics, the peak wavelength of the planar OLED
spectra got blue-shift and the
full-width-at-half-maximum (FWHM) of its spectra
decreased with increasing the viewing angles due to the
microcavity theories. After MAFs are attached to the
OLED, the FWHM of the OLED spectra decreased linearly by
increasing the fill factor of the MAFs. We also observe
blue shifts at different viewing angles which is the
evidence that the waveguiding modes are being extracted.
The saturation phenomena of efficiency enhancement imply
that high fill factor and large height ratio of MAFs
will certainly benefit for efficiency enhancement,
however, full factor cases are not always the most
desirable. Optimal fill factor and height ratio, which
may be less than unity, will gain the best efficiency
enhancement, suffer from less color deviation, and make
fabrication easier.
© 2011 IEEE
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