Semiconductor Planarization for OLED Brightness Uniformity

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Solution Overview

Problem

Existing organic light emitting device manufacturing methods, particularly full evaporation technology, face low material utilization rates and difficulties in producing high-resolution devices, while printing technology suffers from micron-sized foreign particles causing uneven brightness issues due to bright or dark spots, leading to overall brightness inconsistencies.

Innovation Solution

An organic light emitting device is fabricated with a semiconductor layer covering the indium tin oxide layer to ensure even thickness, using materials like indium zinc oxide or indium germanium zinc oxide, deposited via chemical vapor deposition, physical vapor deposition, or spin coating, and a pixel defining layer with a barrier structure and functional layer applied via inkjet printing to prevent brightness irregularities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If printing technology is used to prepare organic light emitting devices, then material utilization rate increases and manufacturing cost decreases, but foreign particles cause uneven brightness

Engineering Contradiction:

Improvematerial utilization rateVSAvoidbrightness uniformity

Core Design Contradiction:

Loss of substanceVSReliability

Solution Approach 1:

A planarization layer is introduced as an intermediary between the substrate and the functional layers. This planarization layer covers and encapsulates foreign particles present on the substrate surface, preventing them from causing brightness defects in the final device while allowing the printing process to continue with its high material utilization rate

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The foreign particles are effectively removed from the optical path by embedding them within the planarization layer. The problematic particles are extracted from the functional structure and isolated in the planarization layer, preventing their harmful effect on brightness uniformity

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of manufacture

If full evaporation technology is used, then manufacturing maturity improves, but material utilization rate decreases and high-resolution capability is lost

Engineering Contradiction:

Improvemanufacturing maturityVSAvoidmaterial utilization rate

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The patent merges the advantages of both full evaporation technology (manufacturing maturity, process stability) and printing technology (high material utilization rate, high resolution capability). The planarization layer approach enables printing technology to overcome its foreign particle issue, allowing both methods' strengths to be combined in a single manufacturing process

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If full evaporation technology is used, then manufacturing maturity improves, but device resolution capability decreases

Engineering Contradiction:

Improvemanufacturing maturityVSAvoiddevice resolution

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

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 effectively prevents uneven brightness by covering foreign particles on the indium tin oxide layer, ensuring overall even brightness and high-resolution capabilities with reduced manufacturing costs compared to traditional methods.

Implementation Method 1

The semiconductor layer is made by chemical vapor deposition, physical vapor deposition, spin coating, or print

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 2

The semiconductor layer is made by chemical vapor deposition, physical vapor deposition, spin coating, or print

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

The semiconductor layer is made by chemical vapor deposition, physical vapor deposition, spin coating, or print

Methodology Applied

Scientific EffectSpin coating: Spin Coating

Implementation Method 4

The indium tin oxide layer 2 at the bottom is a hydrophilic substance, the surrounding wall structure 41 is a hydrophobic substance

Methodology Applied

Scientific EffectHydrophilic-hydrophobic interaction: Hydrophile

Data Source

PatentUS11552248B2Organic light emitting device and method of manufacturing same

Publication Date: 2023.01.10 SHENZHEN CHINA STAR OPTOELECTRONICS SEMICON DISPLAY TECH CO LTD

AI summary

An organic light emitting device and a method of manufacturing the same are provided. The organic light emitting device, from bottom to top, includes a substrate, an indium tin oxide layer, a semiconductor layer, and a pixel defining layer. The semiconductor layer covers foreign particles on the indium tin oxide layer to make the indium tin oxide layer have an even thickness. The method of manufacturing the organic light emitting device including steps of providing an indium tin oxide layer, providing a semiconductor layer, patterning, and providing a pixel defining layer. The disclosure prevents from uneven brightness (mura) causing from a bright spot or a dark spot appearing at the foreign particles and ensures an overall even brightness of the organic light emitting device by providing the semiconductor layer disposed on the indium tin oxide layer to cover foreign particles on the indium tin oxide layer.