Quantum Dot Light-Emitting Device with Optimized Layer Thickness
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Solution Overview
Problem
The organic EL panel described in Patent Literature 1 suffers from a loss of carrier balance in the blue light-emitting layer, leading to degraded internal quantum efficiency.
Innovation Solution
A light-emitting device comprising sub-pixels with light-emitting layers of varying thicknesses, where the blue light-emitting layer is thicker than the green and red light-emitting layers, to improve carrier balance and quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the blue light-emitting layer is made thinner to improve light extraction efficiency, then light extraction efficiency is improved, but carrier balance is lost and internal quantum efficiency degrades
Solution Approach 1:
The patent applies local quality by making each light-emitting layer have a different thickness optimized for its specific wavelength. The blue light-emitting layer is made thicker than conventional designs to compensate for its shorter wavelength and improve carrier balance, while red and green layers have different thicknesses suited to their respective wavelengths. This localized optimization of thickness for each layer resolves the contradiction between light extraction efficiency and internal quantum efficiency.
2Reliability
If the blue light-emitting layer is made thicker to improve carrier balance, then internal quantum efficiency is improved, but light extraction efficiency may be reduced
Solution Approach 1:
The patent applies parameter changes by systematically adjusting the thickness parameter of each light-emitting layer based on its emission wavelength. The blue layer thickness is increased from conventional thin designs to a specific optimized value that improves carrier balance and internal quantum efficiency. This parameter optimization resolves the contradiction by finding the optimal thickness that balances both light extraction and carrier balance requirements.
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 configuration enhances carrier balance within the light-emitting layers, thereby improving internal quantum efficiency.
Implementation Method 1
an organic electroluminescence (EL) panel that has pixels each including an organic light-emitting layer made of an organic EL material
Data Source
AI summary
A light-emitting device includes a first sub-pixel provided with a first light emitter, and a second sub-pixel provided with a second light emitter and constituting, together with the first sub-pixel, one of a plurality of pixels. The first light emitter has a first cathode, a first anode, and a first light-emitting layer containing a first quantum dot and disposed between the first cathode and the first anode. The second light emitter has a second cathode, a second anode, and a second light-emitting layer containing a second quantum dot and disposed between the second cathode and the second anode. The second quantum dot emits light having a longer light-emission wavelength than the first quantum dot. The first light-emitting layer is thicker than the second light-emitting layer.