Abstract
organic light‐emitting diode (OLED) can enable a greater artificial contrast ratio and viewing angle compared to liquid crystal display (LCD) because OLED pixels directly emit light. There is a shortcoming that the internal quantum efficiency can reach values close to 100%, but about 80% light disperses because of the difference among the refractive indices of the substrate, anode, indium tin oxide (ITO) film, and air. In this paper, three dimensions aspherical microlens arrays (3D A‐MLAs) with substrate modifications are developed to simulate the optical luminous field by using FRED software. This study modified parameters of 3D A‐MLAs such as the diameter, fill‐factor, aspect ratio, dry etching parameters, and electroforming rates of microlens to improve the extraction efficiency of the OLED. In dry etching, not only the aspect ratio with better extraction rate can be obtained by reactive ion etching (RIE) dry etching, but also an undercutting phenomenon can be avoided. The dimensions of 3D A‐MLAs can be accurately controlled in the electroforming process used to make a nickel‐cobalt (Ni‐Co) metal mold to achieve the designed dimensions. According to the measured results, the average luminance efficacy of the OLEDs with 3D A‐MLAs can be enhanced.
Highlights
In this rapid-growing information era, display has become an indispensable information tool
The extraction efficiency of luminance could be increased by many methods, such as using the resonant cavity [4], excitation of surface plasmons [5], insertion of a thin silica aerogel layer of very low refractive index [6], and 2D SiO2/SiNx photonic crystals [7] as well as microlens arrays [8]
Comparing the diameter of 3D AMLAs simulated by FRED with the diameter manufactured by UV cured process, the radius decreased from 70 μm to 69.4 μm
Summary
In this rapid-growing information era, display has become an indispensable information tool. The extraction efficiency of luminance could be increased by many methods, such as using the resonant cavity [4], excitation of surface plasmons [5], insertion of a thin silica aerogel layer of very low refractive index [6], and 2D SiO2/SiNx photonic crystals [7] as well as microlens arrays [8]. Among these technologies, the process of microlens arrays is simple and reliable, so this study analyzed the manufacturing and designed parameters of microlens arrays (MLAs). The luminance will be increased as the contact angle and fill-factor of MLA [9] increase, and the luminance will be decreased as the viewing angle is increases [10]
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