Split Electrode for OLEDs Delaying Moisture Degradation

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Solution Overview

Problem

Organic light-emitting devices (OLEDs) face challenges in maintaining shelf life due to moisture-induced degradation, particularly at the cathode-organic interface, leading to the formation of dark spots and reduced performance.

Innovation Solution

A split electrode configuration is introduced, featuring a first conductive layer, a separation layer with distinct optical properties, and a second conductive layer, which directs moisture-induced defects away from the cathode-organic interface, utilizing a separation layer with a different extinction coefficient and refractive index to prevent delamination and extend device lifespan.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional single-layer electrode is used, then the device structure is simple, but moisture-induced degradation occurs at the cathode-organic interface leading to dark spots and reduced shelf life

Engineering Contradiction:

Improveshelf lifeVSAvoidelectrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electrode is divided into multiple layers: a first conductive layer in contact with the organic layer, a separation layer with distinct optical properties (extinction coefficient and refractive index), and a second conductive layer. This segmentation directs moisture-induced defects away from the cathode-organic interface, preventing dark spot formation and extending shelf life while maintaining reasonable structural complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The separation layer acts as an intermediary between the first and second conductive layers. Its distinct optical properties and positioning create a barrier that redirects moisture-induced degradation pathways, protecting the critical cathode-organic interface from direct moisture attack without requiring complete encapsulation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Length of stationary object

If the electrode layers are placed close together, then the device thickness is reduced, but moisture can more easily reach the cathode-organic interface causing degradation

Engineering Contradiction:

Improvedevice thicknessVSAvoidresistance to moisture degradation

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The separation layer is positioned specifically at the interface region where moisture attack is most problematic. By concentrating the protective function at this critical location rather than uniformly thickening the entire electrode, the design extends moisture resistance while minimizing overall device thickness

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9455417B2Split electrode for organic devices

Publication Date: 2016.09.27 UNIVERSAL DISPLAY CORP

AI summary

A device includes a first electrode, an organic layer disposed over the first electrode and a second electrode disposed over the organic layer. The second electrode includes a first conductive layer, a first separation layer disposed over the first conductive layer, and a second conductive layer disposed over the first separation layer, wherein the first separation layer is not a continuous layer and the first and second conductive layers are bridged where the first separation layer is not continuous. The first separation layer has an extinction coefficient that is at least 10% different from the extinction coefficient of the first conductive layer at wavelength 500 nm, or an index of refraction that is at least 10% different from the index of refraction of the first conductive layer at wavelength 500 nm.