Light Emitting Device Capacitor Vertical Stacking Aperture Ratio
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Solution Overview
Problem
Existing light emitting devices have limitations in the area of capacitors, which affect the efficiency and brightness control of organic EL elements in display devices, particularly in the layout and design of drive circuits on substrates.
Innovation Solution
A light emitting device design that incorporates a capacitor with a third electrode overlapping the light emitting element, an insulating layer, and a configuration of first and second drive transistors connected via this electrode, optimizing the area and aperture ratio for improved brightness control and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitor area is increased to improve charge storage capacity, then the brightness control efficiency is improved, but the device area occupied by the capacitor increases
Solution Approach 1:
The patent transitions from a planar capacitor layout to a three-dimensional stacked structure. The capacitor is formed by stacking the first electrode, insulating layer, and third electrode vertically, allowing the capacitor to occupy the space above the light emitting element rather than requiring additional lateral area. This vertical dimensionality change enables increased charge storage capacity without increasing the device footprint.
Solution Approach 2:
The capacitor structure is nested within the existing device architecture by positioning the third electrode to overlap with the light emitting element area. The capacitor components (first electrode, insulating layer, third electrode) are stacked vertically within the same lateral footprint, effectively nesting the capacitor function within the existing device volume rather than requiring separate dedicated space.
2Reliability
If the capacitor area is increased to improve charge storage capacity, then the brightness control efficiency is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent resolves the aperture ratio conflict by moving the capacitor from a lateral arrangement to a vertical stack. The third electrode overlaps with the light emitting element in the planar view but is separated vertically by the insulating layer. This allows the light to pass through the aperture while the capacitor occupies the vertical space above, eliminating the trade-off between capacitor size and aperture ratio.
Solution Approach 2:
The patent segments the device into distinct functional layers vertically: the light emitting layer for light emission and the capacitor stack (first electrode, insulating layer, third electrode) for charge storage. This segmentation allows each component to occupy its optimal space without interfering with the other's function, enabling both high aperture ratio and sufficient capacitor area.
Data Source
AI summary
A light emitting device includes: a light emitting element including a first electrode, a second electrode opposed to the first electrode, and a light emitting layer provided between the first electrode and the second electrode; a capacitor having a third electrode formed in a position overlapping the light emitting element and an insulating layer provided between the first and third electrodes; a first drive transistor disposed on a first side of the first electrode and having a gate electrode; and a second drive transistor disposed on a second side of the first electrode and having a gate electrode connected to the gate electrode of the first drive transistor via the third electrode.