OLED Exciton Blocking Layer for Efficiency and Stability
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Solution Overview
Problem
Current organic light emitting diodes face challenges in achieving low voltage, high efficiency, and long life span due to limitations in material thermal stability, charge mobility, and interfacial characteristics, particularly with materials like NPB and PEDOT:PSS, which hinder efficient exciton formation and light emission.
Innovation Solution
Incorporating specific organic material layers with compounds represented by Formulas 5 or 6 as exciton blocking layers and compounds represented by Formulas 2 or 3 as electron transport layers between the anode and cathode, respectively, to confine excitons and enhance electron injection and transport characteristics, thereby improving light emitting efficiency and diode longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If NPB is used as hole transport layer material, then ease of manufacture is improved, but thermal stability deteriorates (glass transition temperature of 100°C or lower)
Solution Approach 1:
The patent changes the thermal parameter (glass transition temperature) of the hole transport layer material from 100°C or lower (NPB) to above 100°C (TCTA), resolving the thermal stability issue while maintaining ease of manufacture through solution coating methods
Solution Approach 2:
The patent uses TCTA as a composite hole transport layer material that combines high thermal stability (glass transition temperature above 100°C) with good hole transport properties, replacing pure NPB material
2Ease of manufacture
If PEDOT:PSS is used as hole transport material, then ease of manufacture is improved, but light emitting efficiency deteriorates (LUMO energy level lower than light emitting layer material)
Solution Approach 1:
The patent changes the energy level parameter (LUMO level) of the hole transport layer material to be higher than the light emitting layer material, preventing electron leakage and improving light emitting efficiency while maintaining solution coating manufacturability
Solution Approach 2:
The patent introduces TCTA as an intermediary hole transport layer between the anode and the light emitting layer, mediating the energy level mismatch and preventing electron leakage from the light emitting layer to the electrode
3Device complexity
If conventional organic materials are used, then device complexity is reduced, but charge mobility deteriorates (insufficient hole or electron mobility to balance densities)
Solution Approach 1:
The patent changes the mobility parameter of the organic materials used in each layer, selecting materials with optimized hole mobility (TCTA) and electron mobility (Alq3, BCP) to achieve balanced charge densities and maximize exciton formation
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 proposed structure enables an organic light emitting diode with excellent light emitting efficiency, simple manufacturing, low voltage operation, and extended life span by effectively confining excitons and improving electron transport, outperforming related art in these aspects.
Implementation Method 1
An organic light emitting phenomenon is an example of a conversion of current into visible rays by an internal process of a specific organic molecule. When an organic material layer is interposed between an anode and a cathode, if voltage is applied between two electrodes, electrons and holes are injected from the cathode and the anode to the organic material layer. The electrons and the holes injected into the organic material layer are recombined to form an exciton, and the exciton is reduced to a bottom state to emit light.
Data Source
Figure 1
AI summary
The present invention relates to an organic light emitting diode and a method of manufacturing the same. An organic light emitting diode according to the present invention comprises an exciton blocking layer comprising a compound represented by Formula 1 to confine an exciton to a light emitting layer to prevent light emitting leakage, and thus there is an effect of implementing an organic electroluminescence diode having excellent light emitting efficiency. Further, even though there is no separate electron injection layer, electron injection and light transport characteristics are excellent by comprising an electron transport layer comprising a compound represented by Formula 2 or 3, and thus it is possible to implement an organic light emitting diode having a simple and economical manufacturing process, a low voltage, high efficiency, and a long life span as compared to the related art.