UV Patternable Quantum Dot Matrix with Localized Photoinitiator
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Solution Overview
Problem
In quantum dot LED displays, residual quantum dots often remain after photolithography, leading to unwanted light emission and reduced color purity due to the sensitivity of photoinitiators to blue light, causing blue quantum dots to be present in red or green sub-pixels.
Innovation Solution
A quantum dot LED display apparatus with a lower concentration of photoinitiator in the blue emitting sub-pixels, using quantum dots with a core of CdxZn1-xSe or ZnSeyTe and a shell of CdxZn1-xSeyS, and an organic matrix with a cross-linked charge transport material, along with optimized photolithography processes to minimize residual film and improve patterning precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard concentration of photoinitiator is used in blue emitting LED sub-pixels, then the photolithography process can proceed normally, but residual quantum dots remain and cause unwanted blue light emission in red and green sub-pixels
Solution Approach 1:
The patent applies local quality by using different photoinitiator concentrations in different sub-pixel regions. Specifically, the blue emitting LED sub-pixels contain a lower concentration of photoinitiator (e.g., 0.1-1 wt%) compared to red and green sub-pixels (e.g., 1-5 wt%). This localized differentiation prevents over-curing in blue regions that would cause residual quantum dots to migrate into red and green sub-pixels, thereby eliminating unwanted blue light emission while maintaining patterning precision.
Solution Approach 2:
The patent implements parameter changes by adjusting the photoinitiator concentration parameter specifically for blue emitting sub-pixels. By reducing the photoinitiator concentration in blue regions, the curing characteristics are modified to prevent excessive cross-linking that would trap residual quantum dots. This parameter adjustment resolves the contradiction between achieving complete curing (for patterning precision) and preventing residual quantum dot migration (to avoid harmful blue light emission).
2Object-generated harmful factors
If the photoinitiator concentration is reduced in blue emitting sub-pixels, then residual quantum dots are minimized, but the curing process may be less effective
Solution Approach 1:
The patent uses the photoinitiator as an intermediary substance with differentiated concentrations to mediate between curing effectiveness and residual quantum dot removal. In blue emitting sub-pixels, a lower photoinitiator concentration (0.1-1 wt%) serves as an intermediary that provides just enough curing to prevent excessive residual dots without causing over-curing. In red and green sub-pixels, a higher concentration (1-5 wt%) ensures complete curing. This intermediary approach with variable concentrations resolves the contradiction between effective curing and minimizing residuals.
3Manufacturing precision
If photolithography is used to pattern quantum dots, then spatial precision is improved, but scattered UV light causes residual film to remain in developed areas
Solution Approach 1:
The patent applies local quality by implementing region-specific photoinitiator concentrations across different sub-pixel types. Blue emitting sub-pixels use a lower photoinitiator concentration (0.1-1 wt%) to reduce sensitivity to scattered UV light, preventing residual film formation in developed areas. Red and green sub-pixels use a higher concentration (1-5 wt%) to ensure complete curing despite scattered UV exposure. This localized differentiation resolves the contradiction between spatial patterning precision and residual film elimination.
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 effectively reduces unwanted blue light emission from red and green sub-pixels, enhancing color purity and achieving high resolution displays with improved color gamut by minimizing residual quantum dots and controlling the photolithography process.
Implementation Method 1
an emissive layer for a quantum dot LED may include quantum dots in a charge transporting matrix which is cross-linked by exposure to ultraviolet light
Implementation Method 2
a quantum dot LED which emits blue light
Data Source
AI summary
A quantum dot LED display apparatus includes a substrate having a plurality of banks deposited thereon. A plurality of red emitting LED sub-pixels, green emitting LED sub-pixels, and blue emitting LED sub-pixels are individually disposed between the banks. Each of the red emitting LED sub-pixels, green emitting LED sub-pixels, and blue emitting LED sub-pixels has an emissive layer, wherein each of the emissive layers comprises quantum dots, an organic matrix, and a photoinitiator. A first concentration of the photoinitiator in the blue emitting LED sub-pixels is lower than a second concentration of the photoinitiator in the red emitting LED sub-pixels, and lower than a third concentration of the photoinitiator in the green emitting LED sub-pixels.