Organic Light Emitting Device Host Material Balance
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Solution Overview
Problem
Existing organic light emitting devices face challenges in achieving improved driving voltage, efficiency, and lifetime due to imbalances in hole and electron injection, leading to decreased performance.
Innovation Solution
Incorporating a light emitting layer with a first host and a second host, where the first host has a HOMO level of 5.6 eV to 6.4 eV and the second host has a HOMO level of 5.4 eV to 5.8 eV, with a 0.2 eV or more difference, and a maximum emission wavelength of the mixture being 20 nm or more higher than that of the first host, to enhance the balance of holes and electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single host material is used in the light emitting layer, then the device structure is simple, but the balance between hole and electron injection is poor leading to decreased efficiency and lifetime
Solution Approach 1:
The patent employs a composite host material system consisting of two different host materials (first host with HOMO 5.6-6.4 eV and second host with HOMO 5.4-5.8 eV) combined in the light emitting layer. This composite approach enables simultaneous achievement of balanced charge injection and extended device lifetime, resolving the contradiction between reliability and structural simplicity by using a functional composite rather than a single material.
2Illumination intensity
If the HOMO levels of host materials are closely matched, then the energy alignment is good, but the emission wavelength shift is insufficient to achieve optimal performance
Solution Approach 1:
The patent systematically varies the HOMO energy level parameters of the host materials, establishing specific ranges (first host: 5.6-6.4 eV, second host: 5.4-5.8 eV) with a controlled difference of 0.2 eV or more. This parameter optimization achieves both good energy alignment for charge injection and sufficient emission wavelength shift (20 nm or more), resolving the contradiction between illumination intensity and material selection 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 results in improved driving voltage, efficiency, and extended lifetime of the organic light emitting device by optimizing the balance of holes and electrons, thereby enhancing overall performance.
Implementation Method 1
The organic light emitting device using the organic light emitting phenomenon has characteristics such as a wide viewing angle, an excellent contrast, a fast response time, excellent luminance, driving voltage and response speed
Implementation Method 2
the first host has a HOMO of 5.6 eV to 6.4 eV, the second host has a HOMO of 5.4 eV to 5.8 eV, and a difference between the HOMO of the first host and the HOMO of the second host is 0.2 eV or more
Data Source
AI summary
Provided is an organic light emitting device having improved driving voltage, efficiency and lifetime, the organic light emitting device comprises: a cathode; an anode; and at least one light emitting layer interposed between the cathode and the anode, wherein the light emitting layer includes a first host compound of the following Chemical Formula 1-1 or Chemical Formula 1-2 and a second host compound of the following Chemical Formula 2:where the substituents are as defined in the specification.