Tandem Quantum Dot Emission Layers for High-Luminance Light Extraction
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Solution Overview
Problem
Existing light-emitting devices face challenges in achieving high luminance, long lifespan, and efficient light extraction, particularly in tandem structures where multiple emission layers are stacked.
Innovation Solution
A light-emitting device is designed with a structure that includes a first and second electrode, and an interlayer with multiple emitting units and charge generation units. The interlayer contains a first emission layer made of quantum dots with cadmium (Cd) at a specific atomic ratio, which maintains high photoluminescence efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple emission layers are stacked in a tandem structure to increase luminance, then luminance is improved, but device complexity increases and light extraction efficiency decreases
Solution Approach 1:
The device divides the emission layer into multiple discrete emitting units (first emitting unit, second emitting unit, etc.), each containing quantum dots of specific sizes that emit different wavelengths. This segmentation allows independent optimization of each unit while maintaining overall high luminance through additive color mixing, resolving the contradiction between increased luminance and device complexity.
Solution Approach 2:
The patent introduces charge generation units as intermediate layers between emitting units, creating a vertical stacking architecture. This dimensional organization separates charge generation functions from light emission functions, enabling efficient carrier management in tandem structures without proportionally increasing overall device complexity.
2Illumination intensity
If multiple emission layers are stacked in a tandem structure to increase luminance, then luminance is improved, but light extraction efficiency decreases
Solution Approach 1:
The patent applies local quality by giving each emitting unit specific optical characteristics through controlled quantum dot size distributions. The first emitting unit contains smaller quantum dots for blue-green emission, while the second emitting unit contains larger quantum dots for red emission. This local optimization of emission wavelengths reduces spectral overlap and improves overall light extraction efficiency while maintaining high luminance.
3Illumination intensity
If quantum dots with high photoluminescence efficiency are used to improve luminance, then luminance is improved, but thermal stability deteriorates
Solution Approach 1:
The patent employs composite quantum dot structures with specific cadmium atomic ratios (0.001 to 0.1) combined with shell materials to create core-shell composite quantum dots. This composite structure maintains high photoluminescence quantum yield (0.90 to 1.0) while the shell provides thermal protection, resolving the contradiction between high luminance efficiency and thermal stability.
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 proposed design enhances the thermal stability and efficiency of the light-emitting device, leading to improved luminance, extended lifespan, and increased light extraction efficiency.
Implementation Method 1
the first quantum dots have a photoluminescence (PL) maintenance ratio in a range of about 0.90 to about 1
Data Source
AI summary
Provided are a light-emitting device and an electronic apparatus and an electronic device that include the light-emitting device, the light-emitting device including an interlayer between a first electrode and a second electrode and including an emission layer, wherein the emission layer includes a first emission layer, the interlayer includes m emitting units and m−1 charge generation unit(s) each between neighboring emitting units of the may be emitting units, m is an integer of 2 or more, an emitting unit between the first electrode and a charge generation unit adjacent to the first electrode includes the first emission layer, the first emission layer includes first quantum dots, the first quantum dots include cadmium (Cd) at an atomic ratio of about 0.001 to about 0.1 with respect to total atoms, and the first quantum dots have a photoluminescence (PL) maintenance ratio in a range of about 0.90 to about 1.