Elastomeric Lens for MicroLED Light Extraction and Handling
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Solution Overview
Problem
Conventional pick and place techniques are unsuitable for micro-light emitting diodes (mLEDs) due to their small size, leading to low light extraction efficiency and brightness limitations, and existing methods fail to effectively enhance light extraction in electronic displays.
Innovation Solution
A light emitting diode (LED) with an epitaxial layer forming a mesa structure and an elastomeric material on the light emitting surface, which serves as a lens to collimate light and improve light extraction efficiency, while also facilitating adhesion during pick and place operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional pick and place techniques are used for mLEDs, then the manufacturing process is simple, but the light extraction efficiency is very low due to the small size of mLEDs
Solution Approach 1:
An elastomeric material is introduced as an intermediary layer between the mLED and the pick-up head during transfer, and simultaneously serves as an optical element on the light emitting surface. This intermediary structure enables both effective handling of small mLEDs and enhancement of light extraction efficiency through its lens-like optical properties.
Solution Approach 2:
The elastomeric material performs multiple functions simultaneously: it acts as an interface layer for adhesion during pick-and-place operations, and also functions as an optical component (lens) that collimates and extracts light from the mLED, eliminating the need for separate handling and optical optimization steps.
2Manufacturing precision
If the size of mLEDs is reduced to form sub-pixels, then the display resolution is improved, but the brightness is limited due to low light extraction efficiency
Solution Approach 1:
The elastomeric material is shaped with a curved, lens-like profile on the light emitting surface of the mLED. This curvature focuses and collimates the emitted light, increasing the directional light output and perceived brightness of the small mLED sub-pixels without increasing their physical size.
3Loss of energy
If an elastomeric material is added to the light emitting surface, then light extraction efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The elastomeric material integrates multiple functions into a single component: it serves as the transfer interface for pick-and-place manufacturing and simultaneously acts as the optical lens for light extraction enhancement. This multi-functionality avoids the need for additional separate layers or components that would increase structural complexity.
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 enhances light extraction efficiency and brightness by directing light output from the active layer through the mesa structure and elastomeric lens, increasing the brightness level of microLEDs and enabling more efficient manufacturing processes.
Implementation Method 1
the elastomeric material shaped as a lens collimates the light transmitted from the light emitting region
Implementation Method 2
the light emitted from the active layer is reflected at the mesa structure toward a light emitting region of the light emitting surface
Data Source
AI summary
A light emitting diode (LED) includes an elastomeric material that facilitates adhesive attachment with a pick-up head for pick and place operations. The LED includes an epitaxial layer defining a mesa structure and a light emitting surface. The mesa structure includes an active layer to emit light, and the emitted light is reflected at the mesa structure toward a light emitting region of the light emitting surface and transmitted at the light emitting region. An elastomeric material is on a portion of the light emitting surface, such as the light emitting region or a passive region. At the light emitting region, the elastomeric material may be shaped as a lens that collimates light transmitted from the light emitting region, and also facilitates adhesion to the pick-up head. At the passive region, the elastomeric material facilitates adhesion to the pick-up head without interfering with light emitted from the light emitting region.