Organic Light Emitting Element Blue Light Extraction Efficiency
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Solution Overview
Problem
Organic light emitting elements face challenges in achieving high light extraction efficiency and reducing sheet resistance for blue light emission, particularly in high-definition displays, where the trade-off between light extraction efficiency and sheet resistance value is significant, affecting power consumption and lifespan.
Innovation Solution
The organic light emitting element incorporates a first electrode that reflects incident light, a second electrode allowing light to pass through, an organic light emitting layer, and functional layers with specific optical film thicknesses and refractivity ranges to create two optical paths for blue light emission, with the second electrode being a stack of translucent conductive and metal layers to reduce sheet resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a translucent conductive material (ITO) is used for the cathode, then light extraction efficiency is improved, but sheet resistance value increases
Solution Approach 1:
The cathode is constructed as a composite structure combining a translucent conductive layer (ITO) with a reflective layer (Aluminum). This composite configuration allows the ITO layer to provide light extraction functionality while the reflective layer provides low resistance, solving the contradiction between light extraction efficiency and sheet resistance value.
2Loss of energy
If the optical film thickness of the first functional layer is optimized for blue light resonance, then blue light extraction efficiency is improved, but chromaticity may be affected
Solution Approach 1:
The optical film thickness of the first functional layer is precisely controlled within the range of 48-62 nm to achieve resonance enhancement for blue light. This parameter optimization maximizes blue light extraction efficiency while the reflective cathode structure helps maintain proper chromaticity by reflecting non-blue wavelengths back into the emitting layer.
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
This configuration enhances blue light extraction efficiency and chromaticity while reducing sheet resistance, improving power efficiency and extending the lifespan of the organic light emitting elements.
Implementation Method 1
a first electrode which reflects incident light
Implementation Method 2
an organic light emitting layer which is disposed between the first electrode and the second electrode, and emits at least blue light
Data Source
AI summary
Each of blue light emitting elements includes: a photoanode; a translucent cathode; an organic light emitting layer between the photoanode and the translucent cathode; a first functional layer between the organic light emitting layer and the photoanode; and a second functional layer between the organic light emitting layer and the translucent cathode, and has a resonator structure. The first functional layer has an optical film thickness of 48-62 nm. The translucent cathode is a stack of a first translucent conductive layer, a metal layer, and a second translucent conductive layer stacked in this order from the second functional layer side. The first translucent conductive layer has a refractivity of 2.0-2.4, and a film thickness of 85-97 nm. The metal layer has a refractivity different by 0 to 2.0 from that of the first translucent conductive layer, and has a film thickness of 2-22 nm.