Hole Injection Layer Composition for Lower-Voltage OLEDs
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Solution Overview
Problem
Existing organic electronic devices, such as OLEDs, face challenges in achieving balanced hole and electron injection, leading to high operating voltages and limited efficiency, with a need for improved hole injection layers that can be deposited under conditions suitable for mass production.
Innovation Solution
A hole injection layer comprising a specific combination of a hole transport compound and a metal complex, arranged in two sub-layers, with the hole transport compound having a formula (I) and the metal complex having a formula (II), allowing for improved hole injection and transport, and being suitable for vacuum thermal evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional hole injection layers are used, then device structure is simple, but operating voltage is high and efficiency is limited
Solution Approach 1:
The hole injection layer is divided into two distinct sub-layers: a first sub-layer comprising a hole transport compound and a second sub-layer comprising a metal complex. This segmentation allows each sub-layer to perform specialized functions, with the hole transport compound optimizing hole injection and the metal complex enhancing charge balance, thereby reducing operating voltage while maintaining manageable structural complexity through modular design
Solution Approach 2:
The invention employs a composite hole injection layer structure combining organic hole transport compounds with metal complexes. This composite approach leverages the complementary properties of both material classes - the organic compound provides efficient hole transport while the metal complex contributes to improved charge balance and reduced operating voltage, achieving superior overall device performance
2Productivity
If hole transport compound HOMO level is optimized to be further away from vacuum level, then charge balance and efficiency are improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention systematically adjusts the HOMO level parameter of the hole transport compound by selecting specific molecular structures and substituents. By changing these chemical parameters, the HOMO level is optimized to be further away from the vacuum level, which improves charge balance and device efficiency while the patent provides guidance on acceptable ranges to maintain manufacturing feasibility
3Ease of manufacture
If hole injection layer is optimized for mass production, then ease of manufacture improves, but device performance may be compromised
Solution Approach 1:
The invention replaces complex multi-step deposition processes with vacuum thermal evaporation, a well-established technique suitable for mass production. The hole transport compound and metal complex are selected to be compatible with this deposition method, allowing efficient fabrication while maintaining device performance through proper material selection and layer architecture
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 solution results in organic electronic devices with reduced operating voltage and enhanced efficiency, suitable for mass production, by optimizing the HOMO level of the hole transport compound to be further away from the vacuum level, thereby improving charge balance and device performance.
Implementation Method 1
holes injected from the anode move to the EML, via the HIL and HTL
Implementation Method 2
holes injected from the anode move to the EML, via the HIL and HTL
Implementation Method 3
The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to an organic electronic device comprising an anode layer, a cathode layer and a hole injection layer, wherein the hole injection layer is arranged between the anode layer and the cathode layer and wherein the hole injection layer comprises a hole transport compound and a metal complex.