OLED Electron Transport Layer Segmentation for Thermal Stability
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Solution Overview
Problem
Existing organic light emitting diodes (OLEDs) face challenges with low luminous efficiency and short luminous lifespan due to the limitations of fluorescent materials and the instability of phosphorescent materials used in commercial applications.
Innovation Solution
The use of an OLED structure with a first electron transport layer containing a spiro-structured fluorenyl group and a second electron transport layer with an anthracenyl group, enhancing thermal stability and electron mobility, is introduced to improve luminous properties and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent material is used to improve luminous efficiency, then luminous efficiency is improved, but luminous lifespan becomes short
Solution Approach 1:
The electron transport layer is divided into two distinct layers: a first electron transport layer adjacent to the emitting material layer and a second electron transport layer adjacent to the second electrode. This segmentation allows each layer to be optimized for different functions, with the first layer focusing on thermal stability and exciton management, and the second layer on electron transport efficiency, thereby resolving the contradiction between luminous efficiency and lifespan
Solution Approach 2:
Different electron transporting materials are selected for different positions within the electron transport layer. The first electron transport layer uses materials with specific properties (represented by Chemical Formula 1) optimized for thermal stability and exciton blocking, while the second electron transport layer uses materials (represented by Chemical Formula 4) optimized for electron transport. This local differentiation allows the structure to simultaneously achieve high luminous efficiency and extended lifespan
2Device complexity
If conventional electron transport layer is used, then device structure is simple, but thermal stability is insufficient
Solution Approach 1:
The electron transport layer is segmented into two functional layers with distinct material compositions and roles. The first electron transport layer (adjacent to emitting material) uses materials represented by Chemical Formula 1 with specific molecular structures optimized for thermal stability and exciton blocking, while the second electron transport layer uses materials represented by Chemical Formula 4 optimized for electron transport. This segmentation enables enhanced thermal stability without excessive complexity
Solution Approach 2:
The patent specifies particular molecular structure parameters for the electron transporting materials in each layer. The first layer materials have structures represented by Chemical Formula 1 with specific substituent groups (R1-R4, L1-L3, m-n parameters), while the second layer materials have structures represented by Chemical Formula 4 with specific substituent groups (R21-R24, L21-L23, s-t parameters). These parameter optimizations enable enhanced thermal stability while maintaining manageable device complexity
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 configuration maintains high light intensity and extends the luminous lifespan of OLEDs, even under high temperature conditions, by ensuring efficient electron transport and improved thermal resistance.
Implementation Method 1
an electron transport layer disposed between the at least one emitting material layer and the second electrode, wherein the electron transport layer includes a first electron transport layer disposed between the at least one emitting material layer and the second electrode; and a second electron transport layer disposed between the first electron transport layer and the second electrode
Implementation Method 2
The first electron transporting material can have a structure of Chemical Formula 1... at least one of R1 and R2 is an unsubstituted or substituted spiro-fluorenyml group... The second electron transporting material can have a structure of Chemical Formula 4... at least one of R21 and R22 is an unsubstituted or substituted anthracenyl group
Data Source
AI summary
An organic light emitting diode (OLED) includes an emissive layer with at least one emitting part includes at least one emitting material layer, a first electron transport layer and a second electron transport layer disposed sequentially between two facing electrodes, wherein the first electron transport layer includes a first electron transporting material of a benzimidazole-based compound substituted with at least one spiro-structured fluorenyl group and the second electron transport layer includes a second electron transporting material of a benzimidazole-based compound substituted with at least one anthracenyl group. The first electron transport including the first electron transport material with excellent thermal stability is disposed adjacently to the emitting material layer so that the OLED can maintain good luminescent intensity in an environment of high temperature and implement beneficial luminous properties.