OLED Double Bank Structure Aperture Ratio
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Solution Overview
Problem
The existing organic light emitting diode (OLED) displays face a reduction in aperture ratio due to non-fill areas when depositing organic light emitting material, leading to deteriorated video data quality and parasitic capacitance issues.
Innovation Solution
A double bank structure is implemented, where a first bank defines the emitting area and a second bank exposes a larger opening area, allowing the organic light emitting layer to be deposited without non-fill areas, thereby eliminating aperture ratio loss and enhancing the display's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single bank structure is used to define the emitting area, then the manufacturing process is simple, but non-fill areas form during organic material deposition causing aperture ratio reduction
Solution Approach 1:
The single bank structure is divided into two separate banks: a first bank that defines the emitting area and a second bank that exposes additional areas. This segmentation allows the organic light emitting layer to be deposited completely without non-fill areas while maintaining manufacturing feasibility through sequential formation processes.
Solution Approach 2:
The second bank is positioned at a different spatial dimension relative to the first bank, creating a stepped configuration. This dimensional arrangement enables the organic material deposition process to access and fill all necessary areas that would otherwise be inaccessible in a single-plane bank structure.
2Area of stationary object
If the bank opening area is reduced to define the emitting area, then the aperture ratio decreases, but parasitic capacitance is reduced
Solution Approach 1:
The bank structure is segmented into two functional parts: the first bank's opening defines the emitting area for light output, while the second bank's opening provides additional exposure area for complete organic material deposition. This segmentation allows the emitting area to be optimized for aperture ratio while the additional exposed areas serve the functional purpose of eliminating non-fill regions, thereby reducing parasitic capacitance effects.
3Manufacturing precision
If the organic light emitting layer is deposited to fill the bank opening area, then non-fill areas are eliminated, but the aperture ratio is reduced
Solution Approach 1:
The bank structure is divided into two banks with different functions: the first bank defines the emitting area boundaries, while the second bank provides additional exposure area. This segmentation enables the organic light emitting layer to be deposited completely across all necessary areas without compromising the aperture ratio, as the second bank's additional exposure area does not contribute to light emission but ensures complete material coverage.
Solution Approach 2:
The second bank acts as an intermediary structure that facilitates complete organic material deposition. It provides the necessary exposure area for the deposition process to reach all required regions without requiring the first bank's opening to be enlarged, thus maintaining the aperture ratio while eliminating non-fill areas.
Data Source
AI summary
The present disclosure relates to an organic light emitting diode display having high aperture ratio. The present disclosure suggests an organic light emitting diode display comprising: a substrate having a plurality of pixel area arrayed in a matrix manner; an anode electrode formed within the pixel area on the substrate; a first bank having an open area exposing most of the anode electrode and defining an emission area; a second bank exposing the open area exposed by the first bank and some upper surface of the first bank; an organic light emitting layer covering the some upper surface of the first bank by the second bank and the most of anode electrode exposed by the first bank; and a cathode electrode formed over the substrate having the organic light emitting layer.