Improved light out-coupling in organic light emitting diodes employing ordered microlens arrays

Abstract

We demonstrate that ordered microlens arrays with 10 m diam poly-dimethyl-siloxane lenses attached to glass substrates increase the light output of organic light emitting devices ͑OLED͒ by a factor of 1.5 over unlensed substrates. The lenses, which are considerably smaller than, and not aligned to the OLEDs, outcouple light that is emitted outside of the escape cone of the substrate. We show that an electrophosphorescent device based on a fac tris͑2-phenylpyridine͒Iridium ͑Ir͑ppy) 3 ͒ doped emitting layer has its external quantum efficiency increased from 9.5% using a flat glass substrate, to 14.5% at low current densities using a substrate with microlenses. No change in the emission spectrum is observed for different viewing angles using the lens arrays.

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.…”

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

“…For example, the glass mode can be extracted from the substrate by forming either a microlens array or a diffusing layer on the glass substrate [5][6][7][8][9][10][11][12]. The internal bulk or interface structures were modified to extract the light trapped in the organic layers by, for example, reflector modification, insertion of low-index grids in the organic layers, interface or structure modification of the organic and ITO layers, and patterning the ITO electrodes along with an insertion of a high-conductivity polymer layer [13][14][15][16][17][18][19][20].…”

Fabrication of Photonic Crystal Structures on Flexible Organic Light-Emitting Diodes by Using Nano-Imprint and PDMS Mold

“…OLED is often to combine with nano/micro structure to enhance light extraction whose common methods are as follows: application scattering layer on the OLED surface [1], to cover an ordered microlens arrays [2], using anodic aluminum oxide (AAO) ¿lms [3], and applied photonic crystal technology [4][5][6][7]. In the technology of photonic crystal, usually use nanoimprint lithography (NIL) to fabricate.…”