Organic Light-Emitting Element With pKa Electron-Injection Layer
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Solution Overview
Problem
Current light-emitting devices using organic compounds face challenges in achieving high-resolution displays with favorable characteristics, display quality, and yield, particularly due to contamination issues during photolithography processes and the difficulty in electron injection without increasing the drive voltage.
Innovation Solution
A light-emitting element structure featuring an organic compound layer with a light-emitting layer and an electron-injection layer containing an organic compound with a basic skeleton and an acid dissociation constant pKa of 1 or more, allowing for photolithography processing without contamination and effective electron injection, even without alkali metals or their compounds, thereby enabling high-resolution display manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography technique is used to pattern organic layer for high-resolution display, then manufacturing precision is improved, but contamination occurs during the photolithography process
Solution Approach 1:
An electron-injection layer comprising an organic compound with a basic skeleton and pKa≥1 is introduced as an intermediary between the patterned organic compound layer and the electrode. This intermediary layer prevents contamination from propagating to functional layers while enabling effective electron injection, thus resolving the contradiction between achieving high manufacturing precision through photolithography and preventing contamination during the process.
2Reliability
If conventional electron-injection methods are used, then electron injection is achieved, but drive voltage increases
Solution Approach 1:
The invention changes the chemical parameter (acid dissociation constant pKa) of the organic compound in the electron-injection layer to be 1 or more, specifically using compounds with basic skeletons. This parameter change enables the compound to effectively donate electrons to the electrode while maintaining low drive voltage, thus improving electron injection efficiency without increasing power consumption.
3Reliability
If alkali metals or their compounds are used to improve electron injection, then electron injection efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention replaces expensive and complex alkali metal-based electron-injection materials with organic compounds having basic skeletons and pKa≥1. These organic compounds achieve comparable or superior electron injection efficiency while being easier to manufacture, store, and process, thus reducing device complexity and manufacturing difficulty.
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 approach allows for the production of high-resolution display devices with improved characteristics and yield by preventing contamination during photolithography and maintaining low drive voltage, ensuring favorable display quality and efficiency.
Implementation Method 1
Light-emitting elements (also referred to as light-emitting devices) including organic compounds and utilizing electroluminescence (EL)
Implementation Method 2
Carriers are injected by application of voltage to the device, and recombination energy of the carriers is used, whereby light emission can be obtained from the light-emitting material
Data Source
AI summary
A plurality of light-emitting elements having a structure in which an organic compound layer as a whole is processed with a photolithography technique is provided. A light-emitting element is formed over an insulating layer and includes a first electrode, a second electrode, and an organic compound layer. The organic compound layer is positioned between the first electrode and the second electrode. The organic compound layer includes a light-emitting layer and an electron-injection layer. The electron-injection layer is in contact with the second electrode, and the electron-injection layer includes an organic compound having a basic skeleton and an acid dissociation constant pKa of 1 or more. Layers included in the organic compound layer have substantially the same contour, and the organic compound layer is separated from organic compound layers of the other light-emitting elements of the plurality of light-emitting elements.