The light out-coupling efficiency of top-emitting OLED devices with different micro-structures was investigated with the aid of software FDTD solutions. The micro-structures included surface grating, wavy shape and spherical micro lens respectively. The simulation results indicated that the micro-structure was helpful to improve the light out-coupling efficient of OLED. Further more a complex spherical crown surface micro-structure was designed. The light out-coupling efficient of top-emitting OLED with the complex spherical surface improved 14% compared that of the device with smooth surface and 6% compared with micro lens.
The escaped and trapped emission of organic light-emitting diodes was investigated by an integrating sphere and a
fiber spectrometer. It was found that the ratio of escaped emission to the escaped and trapped in the substrate emission is
71%. In order to explain our experimental results, we extended the half-space dipole model, in which the dipole radiation
pattern is taken into account. The calculated escaped and trapped emission of devices agreed well with our experiments.
Our experimental and theoretical results is expected to be an instruction to the optimization of device structures for
improving the out-coupling efficiency.
Optical microcavity is a high quality factor micro-cavity with a size of the resonant wavelength. By using of
spontaneous emission modulation of organic gain medium, an organic microcavity laser can be achieved. In this paper, a
metal Ag-dielectric DBR mirrors mixed organic micro-cavity structure was proposed in this paper. And the influences of
center wavelength, growth sequence and the cycle number of DBR, and the thickness of Ag mirror and organic
light-emitting layer on performance of Ag-DBR mixed organic micro-cavity were investigated by simulation. And then
according to PL characteristics of Alq3:DCM(0.5wt%), an optimal metal Ag-DBR microcavity structure was designed,
and based on theoretical calculation results, a corresponding microcavity devices (air/Ag/organic layer/DBR/glass) was
fabricated. The experimental and theoretical simulation results are in good agreement. The results show that the
calculation method of ours is of great guided significance on the fabrication of metal-DBR organic microcavity lasers.
We studied the interaction between sub-picosecond laser pulse with fused silica. Breakdown threshold, electron collision time and nonlinear propagation dynamics were investigated to study the ionization dynamics and nonlinear propagation process of laser pulse. Electron collision time was measured to be about 1.7fs when the electron density is about 1019cm-3. Measurements on single shot laser-induced breakdown threshold in bulk fused silica were performed for pulse duration tp ranging from 240fs to 2.5ps when objective with different numerical aperture (NA) were used. It was found that the threshold tendency was depend on effective NA. Numerical simulations based on the nonlinear propagation model revealed that the defocusing effect of the bulk plasma was responsible for the different tendencies. Multi-foci was found at high incident pulse energy and the numerical simulations revealed that it was concomitant with pulse reshaping and refocusing by self-focus.