Optical Simulation and Analysis of Top-Emitting Organic Light Emitting Device with a Microcavity
Date Issued
2005
Date
2005
Author(s)
Hsiao, Chia-Chiang
DOI
en-US
Abstract
In this thesis, we use a rigorous electromagnetic model to investigate the optical properties of top-emitting organic light-emitting device (TOLED). TOLED can be regarded as a one dimensional Fabry-Perot microcavity because the total multi-layer thickness is on the order of visible wavelength. The intensity and spectral distribution are strongly dependent on the device structure and viewing angle. We calculate the optical characteristics of TOLEDs with three different cathode materials which are ITO, silver, and silver capped with ZnSe, to optimize the output intensity at normal direction and the total output flux. The cathode consists of sliver capped with ZnSe has the maximum normal direction intensity and total flux, while the ITO case has the lowest. The normal direction optimized EL spectra are independent of the viewing angle, while the flux optimized EL have obviously blue-shift.
For better viewing angle characteristic, we first optimize the device at the normal direction, then, tune the total optical length by changing the phase caused by the anode to tune the EL spectrum. A ZnSe layer is inserted between the anode and the metal mirror to change the anode phase and reflectivity. When varying the ZnSe thickness at the anode side, the phase-shift caused by the anode and the total optical length L change. With increasing the ZnSe layer, the EL spectrums have obviously red shift, and still angle-independent. Besides, with thick ZnSe thickness, the reflectivity of anode slightly increases and result in higher output intensity. By using this methodology, pure RGB devices can be obtained.
Subjects
有機發光元件
光學模擬
微共振腔
OLED
simulation
microcavity
Type
thesis