Study on Optical Characteristics of Organic Light-Emitting Devices
Date Issued
2006
Date
2006
Author(s)
Chen, Kuan-Yu
DOI
en-US
Abstract
Due to the waveguiding effect of the glass substrate, organic layers
and/or transparent electrode, only portion of light escape outside the
atmosphere and be detected by the human eyes. Hence, the efficiency
improvement is considered as an important issue for an organic
light-emitting device (OLED). In this thesis, we investigate the luminous
enhancement effect of different microlens array films (MAFs) attachment
to a bottom emission OLED (BOLED) experimentally. Besides, we also
establish a theoretical program to simulate the optical characteristics of a
top-emission OLED (TOLED) with dielectric and passivation layers.
MAF-BOLED with higher coverage ratio, smaller base area and
higher height ratio exhibits higher luminous efficiency. The normal
direction luminous efficiency of 42.5% enhancement and luminous power
efficiency improvement of 45% are shown. The image blur phenomenon
due to MAFs attachment is quantitatively defined and it is found to be
positively related to luminous enhancement ratio. We demonstrated a
MAF, which has acceptable blur-width of 45 μm and more than 20%
white light efficiency enhancement on an active-matrix OLED
(AM-OLED).
In our TOLED simulation, we validated the correctness of the
program and the design rules are given. We conclude that TOLED
devices, which have: (1) total optical cavity thickness of half the desired
wavelength, (2) the optical distance between dipole and the reflective
anode of quarter of the desired wavelength, and (3) the anode reflectivity
larger than that of cathode by around 16%, have optimized peak intensity
in desired wavelength.
Subjects
有機發光元件
上發光
微透鏡
光學模擬
增光
保護層
OLED
TOLED
top-emission
microlens
optical simulation
light extraction enhancement
passivation
dielectric
Type
thesis