OLED Transmittance Control Layer Suppressing Resonance
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Solution Overview
Problem
Full-color OLEDs face challenges in achieving proper color balance due to differences in luminance efficiency between red, green, and blue emission layers, leading to issues with white balance and resonance effects caused by the thickness of the organic layer.
Innovation Solution
An organic light emitting display device with a substrate, a reflective first electrode, an organic layer configured to emit white light, and a transmittance controlled layer (TCL) with an optical path length of 260 Å to 1520 Å is used, along with a partially reflective cathode electrode and an optical layer to reduce resonance effects and achieve uniform transmissive spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transflective material is used for the second electrode to achieve light extraction, then light output is improved, but resonance effects occur causing non-uniform electroluminescence spectrum and color shift
Solution Approach 1:
A transmittance controlled layer is introduced as an intermediary component between the transflective second electrode and the organic layer. This layer mediates the optical interaction by controlling light transmittance and suppressing resonance effects, allowing the transflective electrode to maintain its light extraction function while preventing the harmful resonance that causes spectral non-uniformity and color shift.
2Illumination intensity
If the organic layer thickness is increased to improve light emission, then luminance is enhanced, but resonance effects become more significant causing wavelength variations and color inconsistency
Solution Approach 1:
The transmittance controlled layer serves as a buffer intermediary between the organic layer and the external environment. It controls the optical path and suppresses resonance effects that would otherwise be amplified by increased organic layer thickness, enabling high luminance while maintaining color consistency across different viewing angles.
3Stability of the object's composition
If different current values are applied to R, G, and B emission layers to achieve white balance, then color balance is improved, but device complexity and control difficulty increase
Solution Approach 1:
Instead of controlling multiple current parameters for different emission layers, the invention changes the optical parameter (transmittance) of the transmittance controlled layer. This single parameter adjustment compensates for luminance efficiency differences among R, G, and B layers, achieving white balance through optical modulation rather than complex electrical control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures more uniform peak heights in the electroluminescence spectrum and improved color balance, minimizing the impact of resonance effects and wavelength variations, resulting in enhanced luminance and color consistency across different viewing angles.
Implementation Method 1
a resonance effect may occur because the second electrode is formed of a transflective material. Three peaks for R, G, and B light in the electroluminescence (EL) spectrum thereof may not be uniform because of the resonance effect
Implementation Method 2
a transmittance controlled layer (TCL) formed on the second electrode, the transmittance controlled layer having an optical path length of about 260 Å to about 1520 Å
Implementation Method 3
the first electrode comprising a reflective layer, the reflective layer being substantially reflective to visible light
Implementation Method 4
holes and electrons recombine with each other in the emission layer to generate excitons. When these excitons transition from an excited state to a ground state, light is emitted
Data Source
AI summary
An organic light emitting display device (OLED) suppressing a resonance effect and having an enhanced luminance, and a method of fabricating the same, are disclosed. One embodiment of the OLED includes: a substrate; a first electrode disposed over the substrate and having a reflective layer; an organic layer disposed over the first electrode and having a white emission layer; a second electrode disposed over the organic layer; and a transmittance controlled layer (TCL) disposed over the second electrode and having an optical path length of about 260 to about 1520 Å.