Light-Emitting Element Side Surface Light Shielding
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Solution Overview
Problem
Conventional flip-chip light-emitting devices experience light loss and reduced luminance due to light extraction through a light-transmitting substrate, particularly on the side surfaces, leading to inefficiencies in light extraction efficiency.
Innovation Solution
A light-emitting element configuration that includes a semiconductor structure layer, a light-transmitting substrate, a wavelength conversion layer, a light-transmitting covering member with a refractive index lower than the substrate, and a light-shielding member, where the light-transmitting covering member covers at least part of the side surface of the substrate, and the light-shielding member entirely covers the side surfaces, including those of the semiconductor structure layer and wavelength conversion layer, to minimize light absorption and enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light is extracted through a light-transmitting substrate in a flip-chip type light-emitting device, then the device structure is simplified and mounting is facilitated, but light loss occurs on the side surface of the substrate and luminance is lowered
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the light-transmitting substrate and the external environment. This resin layer has a lower refractive index than the substrate, creating a refractive index gradient that reduces total internal reflection at the substrate side surface. The intermediary layer acts as a transition medium that facilitates light extraction while maintaining the simplified flip-chip structure.
Solution Approach 2:
The refractive index parameter is strategically modified by applying a resin coating with a lower refractive index than the light-transmitting substrate. This parameter change creates an optimal refractive index gradient at the substrate side surface, reducing light reflection and improving light extraction efficiency without compromising the mechanical or electrical properties of the device.
2Device complexity
If the side surface of the light-transmitting substrate is left exposed, then the device structure remains simple, but light absorption occurs and luminance is reduced
Solution Approach 1:
The resin layer serves as a protective intermediary that covers the exposed side surface of the light-transmitting substrate. This intermediary layer prevents light absorption by the substrate side surface while maintaining optical transparency. The resin coating thus simultaneously protects the substrate and enhances luminance without significantly increasing device complexity.
3Productivity
If multiple reflections occur at the substrate side surface, then light extraction efficiency is reduced, but adding protective layers increases device complexity
Solution Approach 1:
The refractive index parameter of the substrate side surface environment is changed by applying a resin layer with a lower refractive index. This parameter modification reduces total internal reflection and improves light extraction efficiency. The solution achieves significant productivity improvement with minimal increase in device complexity by using a single functional resin layer rather than multiple complex optical elements.
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
This configuration significantly reduces light loss and enhances luminance and light extraction efficiency by preventing multiple reflections and absorption at the substrate surfaces, ensuring high luminance and efficient light output.
Implementation Method 1
a light-transmitting covering member configured to cover at least a part of a side surface of the light-transmitting substrate and have transparency to light from the light-emitting layer
Implementation Method 2
the side surface of the light-transmitting substrate may have a rough surface region in which conical concavities and convexities on an order of submicron are spread and distributed
Implementation Method 3
a light-shielding member configured to entirely cover surfaces including a surface of the light-transmitting covering member, and including a side surface of the semiconductor structure layer, a side surface of the light-transmitting substrate, and a side surface of the wavelength conversion layer
Data Source
AI summary
A light-emitting element and a light-emitting device having low light loss, high luminance, and high light extraction efficiency are provided. The light-emitting element includes: a semiconductor structure layer having a light-emitting layer; a light-transmitting substrate provided on the semiconductor structure layer; a wavelength conversion layer disposed on the light-transmitting substrate; a light-transmitting covering member configured to cover at least a part of a side surface of the light-transmitting substrate and have transparency to light from the light-emitting layer; and a light-shielding member configured to entirely cover surfaces including a surface of the light-transmitting covering member, and including a side surface of the semiconductor structure layer, a side surface of the light-transmitting substrate, and a side surface of the wavelength conversion layer.