Electroluminescent Device Electron Transport Layer Zinc Oxide Nanoparticles
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Solution Overview
Problem
Current electroluminescent devices face issues with reduced external quantum efficiency and lifespan due to interface deterioration between light emitting and auxiliary layers, particularly in devices using semiconductor nanoparticles that include harmful heavy metals like cadmium.
Innovation Solution
An electroluminescent device configuration is developed with a light emitting layer comprising semiconductor nanoparticles without cadmium, paired with an electron transport layer containing zinc oxide nanoparticles, alkali metals, and halogens, which enhances electroluminescent properties and extends device lifespan by passivating defects and improving conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If semiconductor nanoparticles including cadmium are used in the light emitting layer, then high luminance and efficiency are achieved, but external quantum efficiency decreases and lifespan is reduced due to interface deterioration
Solution Approach 1:
An electron transport layer comprising zinc oxide nanoparticles, alkali metals, and halogens is introduced as an intermediary between the light emitting layer and the second electrode. This intermediate layer passivates defects at the interface and improves conductivity, preventing interface deterioration while maintaining high luminance output from the cadmium-containing semiconductor nanoparticles
Solution Approach 2:
The electron transport layer modifies the electrical and optical parameters at the interface by incorporating alkali metals and halogens with zinc oxide nanoparticles. This changes the conductivity and defect states at the interface, improving electron transport and reducing degradation while preserving the high luminance characteristics of the light emitting layer
2Illumination intensity
If semiconductor nanoparticles including harmful heavy metals are used, then high luminance is achieved, but external quantum efficiency and lifespan are reduced
Solution Approach 1:
The electron transport layer acts as a protective intermediary that shields the harmful heavy metals in the light emitting layer from degrading the device over time. By passivating interface defects and improving electron transport, this intermediate layer extends device lifespan while allowing the heavy metal-containing nanoparticles to maintain their high luminance output
Solution Approach 2:
The harmful effects of heavy metals are extracted and isolated by placing them in the light emitting layer while introducing a separate electron transport layer composed of zinc oxide nanoparticles, alkali metals, and halogens. This separation allows the heavy metals to provide high luminance while the electron transport layer protects against their detrimental long-term effects on device lifespan
3Reliability
If interface deterioration occurs between light emitting and auxiliary layers, then device lifespan is reduced, but external quantum efficiency also decreases
Solution Approach 1:
The electron transport layer serves as a mediator that simultaneously improves device lifespan by preventing interface deterioration and maintains high external quantum efficiency by improving electron transport. The zinc oxide nanoparticles with alkali metals and halogens create a stable interface that reduces energy loss while extending device operation
Solution Approach 2:
By changing the electrical parameters at the interface through the electron transport layer, the patent simultaneously improves device lifespan and external quantum efficiency. The modified conductivity and defect states in the electron transport layer reduce energy loss while preventing the interface deterioration that would otherwise limit device lifespan
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 achieves increased external quantum efficiency and prolonged device lifespan by mitigating interface deterioration and eliminating the use of harmful heavy metals, while maintaining high luminance and efficiency.
Implementation Method 1
an electron transport layer disposed between the light emitting layer and the second electrode, wherein the electron transport layer includes a plurality of zinc oxide nanoparticles, and wherein the electron transport layer further includes an alkali metal and a halogen
Implementation Method 2
light emission from the semiconductor nanoparticle may occur when an electron in an excited state resulting from light excitation or an applied voltage transitions from a conduction band to a valence band
Implementation Method 3
A semiconductor nanoparticle including a semiconductor nanocrystal may exhibit a quantum confinement effect, and thereby, demonstrate luminance properties
Data Source
AI summary
An electroluminescent device including a first electrode and a second electrode spaced apart from each other (e.g., each electrode having a surface opposite the other), and a light emitting layer disposed between the first electrode and the second electrode, and an electron transport layer disposed between the light emitting layer and the second electrode, wherein the light emitting layer includes semiconductor nanoparticles, wherein the electron transport layer includes a plurality of zinc oxide nanoparticles, and wherein the electron transport layer further includes an alkali metal and a halogen.