Organic EL Device Recessed Reflective Layer Light Extraction
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Solution Overview
Problem
Organic electroluminescence (EL) devices suffer from low light use efficiency due to the reflection of light components back into the device, reducing forward luminance and overall light extraction efficiency.
Innovation Solution
The device incorporates a base material with a recessed reflective layer, a filling layer with light transmissivity, and electrodes with controlled light transmissivity and reflectance, including a second electrode with 70% or less reflectance and a transparent conductive film, to optimize light extraction and forward luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective layer with a recess is provided to improve light extraction efficiency, then light use efficiency is improved, but forward luminance is reduced because light components are reflected back into the device
Solution Approach 1:
The patent changes the optical parameters of the second electrode by controlling its reflectance to be 70% or less and light transmittance to be 30% or more. This parameter optimization allows the electrode to transmit sufficient light forward while reflecting enough light back into the device to improve overall light extraction efficiency, thus resolving the contradiction between light use efficiency and forward luminance.
Solution Approach 2:
The patent applies different optical properties to different parts of the device: the reflective layer in the recess has high reflectance to bounce light back, while the second electrode has controlled transmittance and reflectance to balance forward light transmission and internal light recycling. This local differentiation of optical properties allows simultaneous improvement of light extraction efficiency and maintenance of forward luminance.
2Illumination intensity
If the second electrode has high light transmittance to improve forward light emission, then forward luminance is improved, but light extraction efficiency is reduced because less light is reflected back into the device
Solution Approach 1:
The patent optimizes the second electrode's optical parameters by setting reflectance at 70% or less and light transmittance at 30% or more. This balanced parameter selection ensures that sufficient light is transmitted forward to maintain high forward luminance, while enough light is reflected back into the device to improve overall light extraction efficiency, resolving the contradiction between these two parameters.
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 significantly improves forward luminance and light use efficiency by minimizing light reflection and maximizing light transmission, enhancing the overall performance of organic EL devices.
Implementation Method 1
Light emitted from the organic light-emitting layer is reflected at the inclined surface of the recess and is then returned to the organic EL element again
Implementation Method 2
a filling layer filled in the recess via the reflective layer, the filling layer having light transmissivity
Implementation Method 3
the second electrode having light transmissivity, wherein the second electrode has a reflectance of 70% or less
Implementation Method 4
the second electrode having light transmissivity, wherein the second electrode has a light transmittance of 30% or more
Data Source
AI summary
An organic electroluminescence device according to one aspect of the present invention includes: a base material having a top surface on which a recess is provided; a reflective layer provided along at least a surface of the recess; a filling layer filled in the recess via the reflective layer, the filling layer having light transmissivity; a first electrode provided at least on an upper layer side of the filling layer, the first electrode having light transmissivity; an organic layer provided on an upper layer side of the first electrode, the organic layer including at least a light emitting layer; and a second electrode provided on an upper layer side of the organic layer, the second electrode having light transmissivity. The second electrode has a reflectance of 70% or less.