Aryl Siloxane Encapsulants for LED Heat Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aryl group-containing siloxane compositions used in light emitting devices discolor at temperatures above 170°C, leading to reduced light output and altered color, due to oxidation of aryl components forming chromophores.
Innovation Solution
Incorporating an alkaline earth metal into the aryl group-containing siloxane compositions during formation, which reduces discoloration at high temperatures without altering curing conditions or affecting physical properties, making them suitable for use as encapsulating layers in light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aryl group-containing siloxane compositions are used in light emitting devices, then light transmission and barrier properties are provided, but discoloration occurs at temperatures above 170°C due to oxidation of aryl components
Solution Approach 1:
An alkaline earth metal compound acts as an intermediary substance between the aryl group-containing siloxane composition and oxygen, preventing oxidation of the aryl components. The metal compound serves as a sacrificial agent that reacts with oxygen or radical species before they can oxidize the aryl groups, thereby preventing chromophore formation and discoloration while maintaining the encapsulant's light transmission and barrier properties
Solution Approach 2:
The invention converts the harmful oxidation reaction into a beneficial protective mechanism by introducing alkaline earth metal compounds that preferentially react with oxygen and radical species. The metal compounds undergo oxidation themselves, sacrificing their stability to protect the aryl groups from oxidation. This transforms the potential harm of high-temperature oxidation into a protective effect where the metal compound absorbs the oxidative stress
2Illumination intensity
If conventional encapsulating layers are used to protect LEDs, then physical protection is provided, but discoloration reduces light output and alters color
Solution Approach 1:
The alkaline earth metal compounds convert the harmful discoloration effect into a beneficial protective mechanism. By sacrificing their own stability through preferential oxidation reactions, these compounds prevent the oxidation of aryl groups that would otherwise form chromophores and reduce light output. The metal compounds absorb oxidative stress, maintaining the encapsulant's optical properties including light transmission and color rendering
Solution Approach 2:
The alkaline earth metal compounds serve as intermediary substances between the aryl group-containing siloxane composition and oxidative environments. These metal compounds intercept oxygen and radical species, preventing them from attacking the aryl groups. This intermediary action preserves the encapsulant's illumination intensity and color properties by blocking the oxidation pathway before chromophores can form
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 inclusion of alkaline earth metal stabilizes the siloxane compositions at high temperatures, maintaining consistent light transmission and barrier properties, ensuring effective protection of LEDs while preventing discoloration.
Implementation Method 1
discolor at temperatures above 170°C, leading to reduced light output and altered color, due to oxidation of aryl components forming chromophores
Implementation Method 2
the reaction product of: (A) an organopolysiloxane having at least two alkenyl groups per molecule; (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; and (C) a heat stabilizing composition comprising an alkaline earth metal; in the presence of (D) a hydrosilylation catalyst
Data Source
AI summary
An aryl group-containing siloxane composition is formed by introducing an alkaline earth-metal as a part of the reaction product of an organopolysiloxane having at least two alkenyl groups per molecule and an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule in the presence of a hydrosilylation catalyst, wherein at least one of the organopolysiloxanes includes an aryl group. The alkaline earth metal may be introduced via a heat stability composition or may alternatively be pre-reacted with the organopolysiloxane having at least two alkenyl groups per molecule. The aryl group-containing siloxane compositions may be utilized as an encapsulating layer for a light emitting device.