Pixel Structure for Solid State Light Emitting Device
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Solution Overview
Problem
Conventional solid-state light emitting devices face limitations in brightness per unit area, shape refinement, and extraction efficiency due to the inherent constraints of individual LED elements and refractive index mismatch, leading to inefficiencies in light emission and high manufacturing costs.
Innovation Solution
A light emitting device with a substrate and an active layer structure containing luminescent centers, utilizing transition layers to reduce electric field requirements and hot carrier effects, and an encapsulant with a closely matched refractive index to minimize total internal reflections, allowing for contiguous and customizable emissive areas with improved extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If individual LED elements are used to construct shaped light emitting devices, then the light source can be shaped and positioned, but the brightness per unit area is limited and the emissive area cannot be contiguous
Solution Approach 1:
The invention segments the light emitting function into multiple discrete pixel elements arranged in an array. Each pixel element contains a semiconductor active region that can be independently controlled, allowing the construction of large-area contiguous emissive surfaces by combining multiple small elements rather than relying on a single large LED
Solution Approach 2:
The invention applies local quality by enabling independent control of each pixel element's light emission characteristics. Each pixel can be individually addressed and controlled to emit light with specific intensity and timing, allowing precise shaping of the overall light beam while maintaining high brightness density in each local region
2Area of stationary object
If individual light emitting elements are positioned close to each other, then the emissive area can be more contiguous, but physical mounting and electrical interconnection become difficult
Solution Approach 1:
The invention merges multiple functions into the semiconductor substrate structure itself. The substrate provides mechanical support, electrical interconnection through conductive layers, and optical extraction pathways, eliminating the need for separate mounting fixtures and complex wiring assemblies that would be required for discrete LED elements
Solution Approach 2:
The invention introduces an intermediary semiconductor layer structure that facilitates both electrical connection and optical emission. The semiconductor active regions are embedded within a broader semiconductor substrate that acts as an intermediary medium, providing both structural support and electrical pathways while enabling direct optical extraction without requiring additional mounting hardware
3Ease of manufacture
If conventional light emitting devices are used, then manufacturing is straightforward, but extraction efficiency is limited by refractive index mismatch
Solution Approach 1:
The invention changes the optical parameters of the semiconductor material system to improve light extraction. By selecting semiconductor materials with refractive indices better matched to common encapsulants and by structuring the semiconductor layers with specific thicknesses and compositions, the device achieves improved light extraction efficiency while remaining compatible with standard semiconductor manufacturing processes
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 enables high brightness per unit area, customizable light shapes, and significantly enhanced extraction efficiency, potentially doubling the efficiency of solid-state lighting compared to conventional technologies, while reducing manufacturing complexity and costs.
Implementation Method 1
an active layer structure supported on the substrate including at least a first active layer with a concentration of luminescent centers for emitting light at a first wavelength
Implementation Method 2
an encapsulant with a closely matched refractive index to minimize total internal reflections
Implementation Method 3
a first transition layer, between the upper transparent electrode and the active layer structure, having a higher conductivity than a top layer of the active layer structure; whereby high field regions associated with the active layer structure are moved back and away from a first contact region
Data Source
AI summary
A light emitting device includes an active layer structure, which has one or more active layers with luminescent centers, e.g. a wide bandgap material with semiconductor nano-particles, deposited on a substrate. For the practical extraction of light from the active layer structure, a transparent electrode is disposed over the active layer structure and a base electrode is placed under the substrate. Transition layers, having a higher conductivity than a top layer of the active layer structure, are formed at contact regions between the upper transparent electrode and the active layer structure, and between the active layer structure and the substrate. Accordingly the high field regions associated with the active layer structure are moved back and away from contact regions, thereby reducing the electric field necessary to generate a desired current to flow between the transparent electrode, the active layer structure and the substrate, and reducing associated deleterious effects of larger electric fields.