Organic Electroluminescence Material Composition for High Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges in achieving high luminous efficiency while maintaining durability, especially when driven at high temperatures, due to limitations in phosphorescent material combinations and charge transportability.
Innovation Solution
A material composition comprising a specific tris-type metal complex with a mixed-type metal complex having two or more kinds of ligands is used, where the compound with a smaller molecular weight is added in a small amount to enhance luminous efficiency and maintain performance at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a phosphorescent metal complex is used to improve luminous efficiency, then luminous efficiency is improved, but durability deteriorates
Solution Approach 1:
The patent uses a composite light emitting layer containing both a phosphorescent metal complex (iridium or platinum complex) and an organic light emitting material. This composite structure allows the phosphorescent material to provide high luminous efficiency through triplet exciton utilization, while the organic light emitting material maintains device durability by reducing the proportion of metal complex in the light emitting layer, thus preventing excessive metal complex accumulation that would deteriorate durability.
2Use of energy by moving object
If a phosphorescent metal complex of shorter wavelength is used to achieve blue light emission with high efficiency, then luminous efficiency is improved, but the available material options become extremely limited
Solution Approach 1:
The patent introduces an organic light emitting material as an intermediary component in the light emitting layer. This organic material works in conjunction with the phosphorescent metal complex to achieve blue light emission with high luminous efficiency, while expanding the range of available material options beyond the extremely limited phosphorescent metal complexes of sufficiently shorter wavelength.
3Use of energy by moving object
If the proportion of phosphorescent metal complex in the light emitting layer is increased to improve efficiency, then luminous efficiency is improved, but charge transportability control becomes difficult
Solution Approach 1:
The patent optimizes the proportion of phosphorescent metal complex in the light emitting layer by combining it with an organic light emitting material. This parameter adjustment allows achieving high luminous efficiency while maintaining controllable charge transportability, as the organic light emitting material compensates for the charge transport issues that would arise from excessive metal complex concentration.
4Use of energy by moving object
If a substituent is introduced into a specific position of a phosphorescent material complex to improve luminous efficiency, then luminous efficiency is improved, but durability is decreased
Solution Approach 1:
Instead of modifying the phosphorescent metal complex with substituents (which improves efficiency but reduces durability), the patent extracts the efficiency-enhancing function to a separate organic light emitting material component. This separation allows the phosphorescent metal complex to maintain its simple, durable structure while the organic material provides the efficiency enhancement through the composite light emitting layer structure.
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 significantly improves luminous efficiency and maintains it even at high-temperature driving conditions without deteriorating the device's durability, by ensuring efficient charge injection and recombination in the light emitting layer.
Implementation Method 1
a phosphorescent material is used with an attempt to achieve high efficiency of the device. For example, an organic electroluminescence device enhanced in the luminous efficiency and durability by using an iridium complex or a platinum complex as the phosphorescent material
Implementation Method 2
the energy of an exciton produced when an electron injected from a cathode and a hole injected from an anode are recombined in the organic layer is utilized for luminescence
Data Source
AI summary
A material for an organic electroluminescence device is provided and contains compounds represented by the following formulae (3a) and (3b). The compound (3a) has a molecular weight smaller than that of the compound (3b), and the material has a content ratio of the compound (3a) to the compound (3b) of from 0.1 to 5,000 ppm.In the formulae, each of R1a to R1i independently represents a hydrogen atom, an alkyl group having a carbon number of 1 to 20, a cycloalkyl having a carbon number of 3 to 8, an aryl group having a carbon number of 6 to 18, an cyano group, or a fluoro group; n is 1 or 2; and La and Lb form one of the specific bidentate ligands.