Enhanced outcoupling efficiency and removal of the microcavity effect in top-emitting OLED by using a simple vapor treated corrugated film

Abstract

We proposed a simple new method to form organic corrugated film. 50 nm tris(8-quinolinolato)aluminum film which was deposited on a glass substrate was put into an uncured ultraviolet (UV) adhesive atmosphere with active ingredient acrylate monomer. After 12 hours of treatment a corrugated film with nano grains was formed, the surface roughness was changed from 1.8 nm to 26 nm, which was caused by solvent-induced crystallization under the uncured UV adhesive atmosphere. We studied the film morphology, UV absorption and photoluminescence. The optical haze effect was also measured. By using the corrugated film in top emitting organic light-emitting diodes, the microcavity effect was eliminated, and the out-coupling efficiency was obviously improved, and the efficiency improvement was a result of the scattering of the surface plasma mode.

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

“…[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. 106 However, a small LED chip size would lead to a nonnegligible sidewall emission, [107][108][109] and the refractive index difference between red LED and green and blue LEDs results in unmatched RGB radiation patterns.…”

Solution-processable donor–π–acceptor type thieno[3,2-b]thiophene derivatives; synthesis, photophysical properties and applications

“…The PL spectra of the compounds were observed to be slightly red-shifted compared to the EL spectra of the films, which could be due to the microcavity effect. [51][52][53] Computational chemistry DFT calculations of the compounds were performed to gain more insight into their structural and electronic states. 51 The gas-phase geometries were optimized by the Gaussian 09 program at the B3LYP/6-31G(d) level, considering that experimental results of organic materials produce good agreement with the predicted results by B3LYP.…”

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

“…Another approach is to randomize the light path, for instance, by inducing a scattering medium inside or outside the device stack 1,3,16−19 or attaching microlens arrays on the top electrode. 13,15,20 While these techniques can reduce the angular color shift, they cannot completely eliminate the problem 1,18,20 and they require complicated fabrication techniques and may cause pixel blurring or crosstalk. 17 In our recent work, we demonstrated a multi-mode OLED (M-OLED) structure with a bottom spacer, which reduces the angular color shift through cavity design.…”

“…One approach is to increase the transmittance of the top electrode, for instance, by reducing the semitransparent metal electrode thickness (5–8 nm), , adding a capping layer (50–100 nm) on the thin metal electrode, ,,, or replacing the top metal contact with a transparent conductive oxide (TCO) such as indium tin oxide (ITO) and indium zinc oxide. ,− However, since these approaches do not affect the reflectivity of the bottom electrode, the angular spectrum shift still remains a problem. Another approach is to randomize the light path, for instance, by inducing a scattering medium inside or outside the device stack ,,− or attaching microlens arrays on the top electrode. ,, While these techniques can reduce the angular color shift, they cannot completely eliminate the problem ,, and they require complicated fabrication techniques and may cause pixel blurring or crosstalk . In our recent work, we demonstrated a multi-mode OLED (M-OLED) structure with a bottom spacer, which reduces the angular color shift through cavity design .…”