Improvement of optical extraction efficiency of organic light-emitting diode using a large area nano-pattern

In order to improve optical extraction efficiencies, we propose a nano-patterned organic light-emitting diode (OLED) which doesn't rely on high precision lithography nor rigorous periodicity. The nano-pattern is fabricated by spin-coating PS (poly-styrene) spheres on the substrate and carrying out reactive ion etching and flattening using dielectric material. The verification of the optical properties of the nano patterns was carried out by fabricating OLED-like structures using quantum dot and distributed Bragg reflector (DBR). As a result, the nano-patterned structure showed a 28% increase in optical efficiency compared to the non-patterned sample. In addition, the use of a prism sheet on the backside of a glass substrate also showed a 23% increase in optical efficiency by disturbing the total internal reflection between glass and air. In this way, the large area nano-patterns can be fabricated and applied to increasing the optical extraction in OLED.