Optical Simulation Study on the Effect of Diffusing Substrate and Pillow Lenses on the Outcoupling Efficiency of Organic Light Emitting Diodes

Abstract

The effect of diffusing substrate and pillow lenses on the outcoupling efficiency of organic light-emitting diodes (OLEDs) was studied by optical simulation based on the point-dipole model. The diffusing substrate included Mie scatterers by which the condition of total internal reflection could be broken. The finite-difference time-domain method was used to obtain the intensity distribution on the transparent electrode of an OLED, which was used as a light source to carry out a ray-tracing simulation of the OLED and the diffusing substrate. It was found that the outcoupling efficiency of the OLED was sensitive to the thickness of organic layers and could be increased by 21.0% by adopting a diffusing substrate in which Mie scatterers whose radius was 2.0 μm were included at the density of 10 7 mm -3 and by 65.5% by forming one pillow lens with the radius of 2 mm on the front surface of the glass substrate. This study revealed that the outcoupling efficiency could be improved by adopting diffusing substrate and pillow lenses along with the optimization of the thickness of each layer in the OLED.

Simulation Study on the Effect of the Emitter Orientation and Photonic Crystals on the Outcoupling Efficiency of Organic Light-Emitting Diodes

“…This two-beam interference makes the OCE oscillate with the thickness of ETL [30,32,33]. In addition, the surface plasmon excitation and absorption in the metal cathode is another pathway of the generated light in OLEDs into heat dissipation, in particular when the emitter is close to the cathode.…”

“…The purpose of this simulation study is to investigate the effect of the emitter orientation in the emitting layer on the OCE of bottomemission OLED with various thicknesses of ETL. In particular, the combined effect of the emitter orientation and photonic crystals on the OCE has been investigated in detail by using the finite difference time domain (FDTD) method [30][31][32][33] and the ray-tracing technique. The detailed dependence of the OCE of OLEDs with a photonic crystal layer on the ETL thickness may be a new aspect of this study and can serve as a new, useful data set which can be considered in the optimization of the OLED layer structure.…”

A hybrid simulated method for analyzing the optical efficiency of a head-mounted display with a quasi-crystal OLED panel

“…A SiNx buffer layer is inserted underneath the ITO to smooth the ITO/HTL interface [18]. The functioning of the actual HMD system with the OLED panels is estimated with a hybrid method which combines the finite-difference timedomain (FDTD) and ray-tracing method [19][20][21]. The Lumerical FDTD Solutions and LightTools software correspond to the wave and ray methods, respectively.…”

Effects of a Dielectric Multilayer Mirror on the Lighting Efficiency of Organic Light-Emitting Diodes Studied by Optical Simulation

“…순수하게 기하광학적 고려만을 하게 되면 발생한 빛의 20% 미만이 에어 모드로 빠져나가는 것으로 계산된다 [3] . 그 동안 많은 연구자들에 의해 OCE를 향상시키기 위한 다양한 광학 구조가 제안되어 왔는데, 마이 크로렌즈 혹은 확산층을 활용해 기판모드를 추출하는 방법 [5][6][7][8][9][10][11][12] , 도파관 모드로 갇히는 빛을 빼내기 위해 OLED의 내부 구조를 다양하게 변형시키는 접근 방법 [13][14][15][16][17][18][19][20] , 플라스몬 손실 을 줄이거나 [21] 다양한 접근법들을 동시에 적용하는 하이브 리드 방법 [22,23] , 발광층 내 발광자의 방향을 조절하는 방법 [24][25][26][27][28][29][30][31] 등이 시도되어 왔다.…”