Core-Shell Color Conversion Particles With Stokes-Shift Band Alignment
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Solution Overview
Problem
Conventional phosphors and core-shell quantum dots face limitations in controllability of emission wavelength, emission peak width, and color purity, while materials like CdSe have toxicity issues, and InP has durability and light emission efficiency problems, and halide perovskites have insufficient material durability.
Innovation Solution
A color conversion particle with a core and a chalcogenide perovskite shell that absorbs excitation light and emits light at the core or interface, featuring band alignment for a Stokes shift, ensuring high absorbance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of quantum dot is increased to increase absorbance, then absorbance is improved, but quantum size effect is lost or light emission efficiency is lowered due to reabsorption
Solution Approach 1:
The quantum dot is divided into core and shell segments with different functions. The core (e.g., CdSe) provides high light emission efficiency and quantum size effect, while the shell (e.g., ZnS) provides enhanced absorbance and protects the core. This segmentation allows each part to optimize its function without compromising the other.
Solution Approach 2:
The patent uses composite material structure combining different semiconductor materials with complementary properties. The core-shell configuration creates a composite quantum dot where the inner core material and outer shell material work synergistically to achieve both high absorbance and high light emission efficiency.
2Reliability
If halide perovskite is used to achieve high absorbance and light emission efficiency, then light emission efficiency is improved, but material durability is insufficient
Solution Approach 1:
A protective shell layer is applied beforehand to cushion and protect the halide perovskite core from environmental degradation. The shell acts as a barrier against moisture, oxygen, and other harmful factors that would otherwise reduce material durability, while allowing the core to maintain its high light emission efficiency.
3Ease of manufacture
If conventional phosphor is used for color conversion, then ease of manufacture is improved, but controllability of emission wavelength and color purity is limited
Solution Approach 1:
The patent utilizes the quantum size effect to control emission wavelength by changing the physical size parameter of the quantum dot. By precisely controlling the diameter of the quantum dot during synthesis, the emission wavelength can be tuned across the visible spectrum, achieving high manufacturing precision for color conversion applications.
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 ensures high absorbance and light emission efficiency with improved durability, overcoming the limitations of conventional materials.
Implementation Method 1
a shell that contains the core and absorbs excitation light
Implementation Method 2
emits light at the core or at the interface between the core and the shell upon receiving the irradiated excitation light
Implementation Method 3
the core and the shell have band alignment that induces a Stokes shift
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
A color conversion particle includes a core; and a shell that contains the core and absorbs excitation light, and emits light at the core or at an interface between the core and the shell upon receiving the irradiated excitation light. The shell is composed of a chalcogenide perovskite, and the core and the shell have band alignment that induces a Stokes shift.