Quantum Dot Light-Emitting Device Two-Phase Layer Structure
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Solution Overview
Problem
Existing quantum dot light-emitting diodes (QLEDs) suffer from low light extraction efficiency due to the presence of optical waveguide modes, which limits the emission of light and reduces external quantum efficiency, as the light-emitting layer is uniformly flat and lacks effective refractive index matching between layers.
Innovation Solution
A quantum dot light-emitting device with a two-phase light-emitting layer structure is introduced, where the first phase has a higher refractive index than the second phase, allowing only light with an incident angle greater than a critical angle to propagate in the first phase and be emitted, while reducing waveguide mode losses and exciton quenching by separating quantum dot aggregates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniformly flat light-emitting layer is used, then the device structure is simple, but light extraction efficiency is low due to optical waveguide modes
Solution Approach 1:
The light-emitting layer is segmented into multiple layers: a first light-emitting layer containing quantum dot aggregates and a second light-emitting layer without quantum dots. This segmentation allows the first layer to emit light while the second layer acts as an optical extraction layer to reduce waveguide modes and improve light extraction efficiency.
Solution Approach 2:
The patent introduces a vertical dimension to the light-emitting layer structure by creating a multi-layered configuration with different compositions and optical properties. This vertical stratification enables control over light propagation paths and extraction angles, overcoming the limitations of a uniform flat structure.
2Illumination intensity
If quantum dot aggregates are present in the light-emitting layer, then light emission is achieved, but exciton quenching occurs which reduces external quantum efficiency
Solution Approach 1:
The patent applies local quality by concentrating quantum dot aggregates specifically in the first light-emitting layer where light emission is needed, while the second light-emitting layer remains free of aggregates to provide optimal optical extraction. This spatial differentiation of material composition optimizes both emission and extraction functions locally.
3Ease of manufacture
If the light-emitting layer lacks refractive index matching between layers, then manufacturing is easier, but waveguide mode losses increase
Solution Approach 1:
The patent changes the optical parameters of the light-emitting layers by using materials with different refractive indices. The first light-emitting layer has one refractive index while the second light-emitting layer has a different refractive index, creating refractive index contrast that disrupts waveguide modes and improves light extraction efficiency.
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 design enhances light extraction efficiency and external quantum efficiency by confining light emission in the first phase, reducing non-radiative recombination pathways, and improving luminous efficiency.
Implementation Method 1
a refractive index of the first phase is greater than a refractive index of the second phase... allowing only light with an incident angle greater than a critical angle to propagate in the first phase and be emitted
Implementation Method 2
The first phase includes a first polymer and a quantum dot material... Light-emitting diodes based on quantum dot materials are known as quantum dot light-emitting diodes (QLEDs)
Implementation Method 3
the second phase further includes nanoparticles, and the nanoparticles are configured to generate localized surface plasmon resonance under irradiation by light of a preset wavelength
Data Source
AI summary
Disclosed in the embodiments of the present disclosure are a quantum dot light-emitting device and a manufacturing method therefor, and a display apparatus. The quantum dot light-emitting device comprises: an anode and a cathode, which are arranged opposite each other; a light-emitting layer located between the anode and the cathode; a hole transport layer located between the anode and the light-emitting layer; and an electron transport layer located between the cathode and the light-emitting layer, wherein the light-emitting layer comprises: a plurality of first phases arranged independently of each other and a second phase located between the first phases, and each of the first phases comprises a first polymer and a quantum dot material.