Electret Charge Patterning for Self-Aligned Color Conversion Pixels
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Solution Overview
Problem
Existing methods for manufacturing optoelectronic devices with colour conversion portions face challenges in aligning and positioning light conversion portions accurately, especially for small pixel pitches, leading to misalignment and performance degradation.
Innovation Solution
A method involving an electret dielectric layer with locally defined non-zero surface potential patterns, using upper electrode layers to polarize diodes, allowing for localized and self-aligned deposition of photoluminescent particles onto specific diodes through electrophoresis or dielectrophoresis, without the need for sequential charge injection or precise buffer positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sequential charge injection by moving AFM tip is used to form electret layer patterns, then localized charge patterns can be created, but the manufacturing process becomes time-consuming and low productivity
Solution Approach 1:
The patent replaces the mechanical sequential writing process (AFM tip moving across the surface) with a parallel field-based approach. An electret layer is first formed covering the entire diode array, then electrical fields are applied through electrode structures to locally modify charge distribution in parallel across multiple locations simultaneously. This substitution of mechanical sequential operation with field-based parallel operation resolves the contradiction between positioning precision and manufacturing speed.
2Productivity
If stamping technique with polarised buffer is used to define charge patterns, then charge patterns can be defined rapidly, but precise positioning becomes difficult for small pixel pitches
Solution Approach 1:
The patent introduces an intermediary electret layer that serves as a charge storage medium between the buffer structure and the diode array. The buffer defines charge patterns through contact, but the electret layer acts as an intermediary that can have its charge distribution subsequently modified by electrical fields applied through electrodes. This intermediary layer decouples the rapid charge pattern definition from the precise positioning requirement, allowing fast initial formation followed by precise field-based adjustment.
Solution Approach 2:
The patent makes the charge distribution in the electret layer dynamic rather than static. After initial charge pattern formation by buffer contact, the charge distribution can be dynamically adjusted by applying electrical fields through electrode structures. This dynamic control allows the system to achieve both rapid initial formation and subsequent precise positioning, resolving the contradiction between speed and accuracy.
3Ease of manufacture
If buffer positioning is performed manually or with simple alignment, then the stamping process is simple, but positioning uncertainty degrades device performance for small pixel pitches
Solution Approach 1:
The patent implements a feedback mechanism where electrode structures apply electrical fields to the electret layer based on detected positioning errors or desired charge patterns. The system can detect the actual charge distribution or diode activation patterns and use feedback control to adjust the electrical fields, thereby correcting positioning uncertainties introduced during the simple buffer contact process. This feedback loop maintains device performance despite simplified alignment procedures.
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
Enables precise and efficient production of colour conversion portions aligned with diodes, even in large arrays with small pixel pitches, ensuring optimal performance and reducing misalignment issues.
Implementation Method 1
upper electrode layers disposed at the front face and adapted to polarise the diodes
Implementation Method 2
applying a potential difference between, on one hand, a temporary electrode disposed on the dielectric layer, and, on the other, the first upper electrode layers, resulting in the formation of first patterns with non-zero surface potential in the dielectric layer
Implementation Method 3
first photoluminescent particles, which are deposited on the dielectric layer only facing the first patterns with non-zero surface potential
Implementation Method 4
deposited on the patterns of electric charges under the effect of a dielectrophoretic force
Implementation Method 5
The light conversion portions may be formed of a bonding array including particles of a photoluminescent material such as yttrium aluminium garnet (YAG) activated by the cerium ion YAG: Ce
Data Source
AI summary
A method for manufacturing an optoelectronic device including an array of diodes and an array of colour conversion portions includes providing the array of diodes, and the upper electrode layers; depositing a dielectric layer having a substantially zero surface potential; applying a potential difference between an electrode and the first upper electrode layers, resulting in the formation of first patterns with non-zero surface potential in the dielectric layer; and producing the first colour conversion portions, by contacting the dielectric layer with a colloidal solution containing first photoluminescent particles.