Quantum Dot Brightening for LED Quantum Yield

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Solution Overview

Problem

The photo-luminescent quantum yield (PLQY) of quantum dots decreases significantly during the processing and incorporation into LED devices, requiring a lengthy 'burn-in' period for recovery, which is not feasible for immediate use.

Innovation Solution

Applying energy, such as light and/or heat, to quantum dots before incorporation into LED devices, and coating them with an insulating layer like silica to enhance stability and PLQY, ensuring they maintain high performance and photostability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If quantum dots are processed and incorporated into LED devices using conventional methods, then device manufacturing is completed, but photo-luminescent quantum yield decreases by over 50%

Engineering Contradiction:

Improvequantum yieldVSAvoidquantum yield stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by performing a brightening treatment on quantum dots before they are incorporated into LED devices. This pre-treatment stabilizes the quantum yield, preventing the typical 50%+ decrease that occurs during conventional processing. The brightening step is performed on the quantum dot ink or solution prior to dispensing into the LED package, thereby establishing stable optical properties in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by modifying the optical and thermal parameters of quantum dots through controlled exposure to light and heat during the brightening process. This changes the quantum dots' internal state, stabilizing their photoluminescent properties and preventing yield degradation during subsequent device operation and manufacturing steps.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If quantum dots undergo conventional processing without brightening, then manufacturing time is reduced, but quantum yield decreases significantly

Engineering Contradiction:

Improvemanufacturing speedVSAvoidquantum yield

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The brightening treatment is performed as a preliminary step before final device assembly, allowing the quantum dots to be pre-stabilized. This approach integrates smoothly into existing manufacturing workflows and can be performed on quantum dot inks or solutions in bulk before dispensing, maintaining productivity while ensuring high quantum yield.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If quantum dots are used without brightening treatment, then immediate device operation is possible, but target quantum yield specifications are not met

Engineering Contradiction:

Improveimmediate device useVSAvoidquantum yield specification

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent performs the brightening treatment as a preliminary step that enables immediate device operation with target quantum yield specifications already met. By stabilizing the quantum dots before incorporation, the treatment eliminates the need for post-manufacturing burn-in periods, allowing devices to be used immediately at full performance.

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If quantum dots are brightened by burning in LED devices, then quantum yield recovers, but considerable time is required before use

Engineering Contradiction:

Improvequantum yieldVSAvoidburn-in time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs the brightening treatment in advance, during manufacturing, rather than requiring post-manufacturing burn-in time. This shifts the time investment from the customer side to the manufacturing side, allowing devices to be shipped and used immediately without requiring customers to wait hours for quantum yield recovery.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The quantum dots self-stabilize their quantum yield through the brightening treatment, which induces structural or surface changes that lock in high quantum yield performance. This self-service mechanism eliminates the need for extended operational burn-in periods to achieve stabilization.

Inventive Principle:

Principle #25Self-service

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 method significantly increases the PLQY of quantum dots, ensuring they meet target specifications immediately upon device operation and maintaining stability throughout the LED device's operational life.

Implementation Method 1

Method and apparatus of applying light and heat to quantum dots to increase quantum yield

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS10544313B2Method and apparatus of applying light and heat to quantum dots to increase quantum yield

Publication Date: 2020.01.28 OSRAM OPTO SEMICON GMBH & CO OHG

AI summary

A method of increasing photo-luminescent quantum yield (PLQY) of QDs to be used as down-converters placed directly on an LED chip includes synthesizing a plurality of quantum dots, applying energy to the plurality of quantum dots to increase PLQY of the plurality of quantum dots, dispensing the plurality of quantum dots onto the LED chip, and curing the LED chip.