Emissive Device Light Shield for Luminance Uniformity
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Solution Overview
Problem
Emissive devices with switching elements connected via contact holes in insulating layers suffer from nonuniform light intensity due to undesirable reflection and emission from the electrode and luminescent layer, respectively, leading to uneven luminance.
Innovation Solution
Incorporating a light shield with lower light reflectivity than the electrode, positioned to block external light and undesirable reflections, and using an auxiliary lead as a conductive light shield to reduce voltage drops and enhance aperture ratio, thereby improving light uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact hole is disposed in the insulating layer to electrically connect the switching element to the first electrode, then electrical connection is achieved, but external light passes through the contact hole and reflects from the electrode surface, causing nonuniform luminance
Solution Approach 1:
A light shield is introduced as an intermediary component between the contact hole and the viewing side. The light shield blocks external light from reaching the electrode through the contact hole, preventing unwanted reflections while maintaining the electrical connection function. This mediator resolves the contradiction by allowing electrical connectivity through the contact hole while blocking the harmful optical path.
2Reliability
If the luminescent layer is formed inside the contact hole, then electrical connection is achieved, but light is emitted from the luminescent layer along the inner surface of the contact hole, causing nonuniform light quantity
Solution Approach 1:
The light shield serves as a mediator that blocks light emitted from the luminescent layer inside the contact hole from reaching the viewing side. By positioning the light shield to cover the contact hole opening, it prevents the unwanted light emission from the luminescent layer's inner surface while preserving the electrical connection through the contact hole structure.
3Illumination intensity
If a light shield is added to block external light and internal reflections, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The auxiliary lead is designed to serve multiple functions: it provides electrical connection as a conductive path and simultaneously acts as a light shield to block external light and internal reflections. By making the auxiliary lead opaque or using it as the light shield, one component performs dual roles, reducing the need for separate dedicated light blocking structures and thereby minimizing device complexity while achieving luminance uniformity.
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 suppresses nonuniformity in light emission by blocking external light and internal reflections, maintaining even luminance and prolonging the life of the luminescent layer through reduced electrical energy usage.
Implementation Method 1
a light shield disposed at a side from which light from the luminescent layer emerges and having a portion covering the contact hole when viewed in a direction perpendicular to the substrate
Implementation Method 2
a luminescent layer disposed between the first electrode and the second electrode
Data Source
AI summary
An emissive device includes a substrate; a switching element disposed on a surface of the substrate; an insulating layer covering the switching element; a contact hole disposed in the insulating layer; a first electrode disposed on a surface of the insulating layer and electrically connected to the switching element via the contact hole in the insulating layer; a second electrode disposed at a side opposite the substrate with respect to the first electrode; a luminescent layer disposed between the first electrode and the second electrode; and a light shield disposed at a side from which light from the luminescent layer emerges and having a portion covering the contact hole when viewed in a direction perpendicular to the substrate.