Light-Emitting Element Organic Layer Hole Injection
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Solution Overview
Problem
The existing light-emitting elements face challenges in improving luminance and maintaining low drive voltage, as they often require efficient hole injection and transport mechanisms between layers.
Innovation Solution
A light-emitting element structure is introduced, featuring a first anode, a first cathode, a first light-emitting layer, a first hole-transport layer with organic material, a first hole-injection layer with inorganic material, and an organic layer containing aromatic compounds that facilitate chemical bonding and enhance hole injection efficiency, thereby improving luminance and reducing drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional hole-injection layer made of metal oxide is used, then the device structure is simple, but the luminance is insufficient due to poor hole injection efficiency
Solution Approach 1:
The hole-injection layer is segmented into two distinct layers: a first hole-injection layer containing inorganic hole-transport material in direct contact with the anode, and a second hole-injection layer containing organic hole-transport material adjacent to the light-emitting layer. This segmentation allows each layer to perform its specialized function optimally, resulting in improved hole injection efficiency and enhanced luminance.
Solution Approach 2:
The invention employs composite material structure by combining inorganic and organic hole-transport materials in separate layers within the hole-injection region. The inorganic material provides stable charge injection from the anode, while the organic material facilitates efficient hole transport to the light-emitting layer, achieving superior overall performance compared to single-material systems.
2Use of energy by moving object
If the drive voltage is reduced to improve energy efficiency, then power consumption decreases, but hole injection efficiency deteriorates leading to insufficient luminance
Solution Approach 1:
The invention optimizes the energy parameters of the hole-injection layers by selecting materials with appropriate HOMO levels and transport properties. The inorganic hole-transport material in the first layer provides low-resistance charge injection at reduced voltages, while the organic material in the second layer ensures efficient hole delivery to the light-emitting layer, maintaining high luminance even at low drive voltages.
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 enhances luminance and maintains low drive voltage by improving hole injection efficiency and reducing energy barriers between layers, resulting in better performance compared to structures without the organic layer.
Implementation Method 1
R1 containing at an end a functional group capable of chemically bonding to the first inorganic hole-transport material
Data Source
AI summary
A light-emitting element includes: anode; a cathode; a light-emitting layer, and containing a light-emitting material; a hole-transport layer, and containing an organic hole-transport material; a hole-injection layer disposed between the anode and the hole-transport layer, and containing an inorganic hole-transport material; and an organic layer disposed between the hole-transport layer and the hole-injection layer. The organic layer contains an aromatic compound having: a functional group R1 capable of chemically bonding to the inorganic hole-transport material; a functional group R2 that is a functional group containing at an end at least one selected from a hydrogen atom, a nitro group, a cyano group, a halogen group, a carboxyl group, an aldehyde group, a hydroxyl group, an ester bond with one to three carbons, an alkyl group with one to three carbons or an amid group; and an aromatic ring to which each of the R1 and the R2 bonds.