Multi-mode Organic Light-Emitting Diode to Suppress the Viewing Angle Dependence

Abstract

A typical top-emitting organic light-emitting diode (OLED) has a strong microcavity effect because of the two reflective electrodes. The cavity effect causes a serious color shift with the viewing angles and restricts the organic layer thickness. To overcome these drawbacks, we design a multimode OLED structure with dual-dielectric spacer layers, which extend the cavity length by more than 10 times. This design completely eliminates the intrinsic cavity effect caused by the top and bottom boundaries and provides freedom for the organic layer thickness. We demonstrate these effects in a white multi-mode OLED using a white emitter, which shows a negligible angular chromaticity shift of Δuv = 0.006 from 0 to 70°and a Lambertian emission profile. The simple design and the perfect angular color profiles make the multi-mode OLED structure promising in large-area displays and solid-state lighting applications.

Ultrabright and stable top-emitting quantum-dot light-emitting diodes with negligible angular color shift

“…To our best knowledge, this is the lowest color shift ever reported for TE QLEDs, even though previous work generally employed multi-mode cavities and scattering layers that are beneficial for reducing color shifts 30,36 . The color shifts of these QLEDs are also smaller than existing mobile display products and OLEDs with ultralong cavity lengths 38,39 . Figure 3c shows the angular dependence of luminance intensity.…”

Prospects and challenges of mini‐LED, OLED, and micro‐LED displays

“…The color shift of an OLED display can be mitigated by applying scattering medium inside the cavity, increasing the transmittance of top electrode, optimizing the cavity length of an OLED device structure. [98][99][100][101][102] However, the trade-off in complicated fabrication process, pixel crosstalk, decreased color purity, and EQE drop should be considered. [103][104][105] In μLED displays, the cavity effect is weak, so the central wavelength of RGB subpixels basically remains unchanged regardless of viewing angle.…”

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

“…Organic light-emitting diodes (OLEDs) have become one of the mainstream technologies in the next generation of displays due to their advantages of light weight, low power consumption, fast response, and flexibility [1][2][3][4]. 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].…”