Curved Mirror Arrays for Light Extraction in Top-Emitting Organic Light-Emitting Diodes

Abstract

The light outcoupling efficiency of a top-emitting organic light-emitting diode (OLED) is only about 20%, and the majority of the light is trapped in the waveguide modes and surface plasmon polariton (SPP) modes. Extracting the trapped modes can reduce the device power consumption and improve the operating lifetime. In this study, we demonstrate a top-emitting OLED structure with a dielectric spacer to suppress the SPP mode and with a patterned back mirror to extract the waveguide modes. We examine and compare several curved mirror arrays and conclude that a micromirror array (μMA) can efficiently extract the waveguide modes while minimizing the absorption loss. The optimized μMA device with a semi-transparent top electrode shows a 36% external quantum efficiency, 2 times higher than the referenced device. This optical design can be easily incorporated into a top-emitting device and has a great potential for displays and lighting applications.

Highly Efficient Red, Green, and Blue Inverted Top‐Emitting Organic Light‐Emitting Diodes with Microstructured TiN Substrate

“…[5,6] Traditional bottomemitting OLEDs (BOLED) affect the aperture ratio when integrated in circuit, while the top-emitting OLED (TOLED) effectively solve this problem with the theoretical aperture ratio reaching 100%. [7][8][9] On the other hand, traditional OLEDs with the electron transporting layer located near the atmosphere are sensitive to water and oxygen, resulting in black spots and shortening the lifetime of the device. [10] In contrast, the water-oxygen sensitive electron transport materials are deposited at the bottom of the device in inverted OLED (IOLED), which greatly improves the lifetime of OLED and makes it easier to be connected to a-Si TFT circuit.…”

High-efficiency top-emitting organic light-emitting diodes based on metal/ITO composite electrodes

“…OLEDs are commonly being divided into two categories according to their architectures, which are bottomemitting OLEDs (BEOLEDs) and top-emitting OLEDs (TEOLEDs) [5][6][7]. Due to the unique top-emitting direction of the TEOLEDs, the driving elements on the substrate will not block the light path and can theoretically enable a 100% aperture ratio of the display unit, which have a broad application prospect in the field of display [8][9][10]. Besides, the emission spectrum of TEOLEDs tends to be narrower due to the micro-cavity effect, thus improving the efficiency and color purity of devices, promoting the applications in ultra-highdefinition displays and micro-displays [11][12][13].…”

32.1: Research of Nanocomposite Materials with High Refractive Index for HLEMS Application

“…Then, it's finally lost in the form of heat energy. [7][8][9] Therefore, it's necessary to use the light extraction technology to improve the light out-coupling efficiency (η) of OLED display, and convert the non-radiation coupling into the radiation light, so as to reduce the OLED power consumption and improve the smartphone standby experience. In this work, the HLEMS technology is used to improve the light out-coupling efficiency (η) of OLED display.…”