Study On The Application Of Microlens Array For OLED

Organic light emitting diodes (OLEDs) have drawn particularly attention due to theirapplications in flat panel displays and solid-state lighting sources，recently. Compared withcathode ray tube (CRT)、liquid crystal display(LCD)，organic light-emitting device exhibitadvantages such as light-weight, self-emission and fast response, and can be flexible. It’sconsidered to be the next generation of lighting source and display application.The internal quantum efficiency of organic light-emitting device has been close to100%with the new phosphorescent light emitting material. However, due to the existence ofdifferent refractive indices among the substrate, anode, organic thin films, and the air, thereare two wave guiding phenomena in the anode/organic layers and substrate of the organiclight-emitting device. Up to now, only20%of the emitted light from the organic layers canobtain in organic light-emitting device. The low out-coupling efficiency becomes the mainlimitation on applications of organic light-emitting device. Therefore, how to improve theout-coupling efficiency of organic light-emitting device becomes a hot research topic.In this paper, we mainly talk about the performance of organic light-emitting device byusing the microlens array film. And I also discussed the different shapes and different formsof microlens array of organic light-emitting devices by the method of Monte Carlo. Theresults show that: In a certain angle range, the microlens array films can certainly improvethe device’s extraction efficiency; we can get the maximum efficiency in the directionperpendicular to the organic light-emitting device substrate; By using the elliptical microlensarrays, it’s not only improving the organic light-emitting device external quantum efficiency,but also changing the orientation angle of a light organic light-emitting device.This article also discusses several factors affecting the microlens array: the fill factor,substrate size and the contact angle of the lens. The results show that the light out-couplingenhancement increases with the increase of the fill factor. The results obtained here indicate that a good fill factor of microlens is the key to enhance the light out-coupling efficiency ofthe organic light-emitting device device. The choice of the contact angle is also important, asthe contact angle increases, the light output is much better, and it can inhibit light output ifthe contact angle is too small. An increase of57%in the light out-coupling with anoptimized elliptical microlens array is achieved over a conventional device without affectingthe electroluminescent spectrum.