Organic Light Emitting Element Gradient Doping
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Solution Overview
Problem
Organic light emitting elements face challenges with low luminous efficiency and high driving voltage due to the low miscibility of organic electron acceptor compounds with hole transporting compounds, leading to inefficient charge injection and transfer characteristics.
Innovation Solution
Incorporating specific organic electron acceptor compounds with strong electron withdrawing groups into the hole injection layer to enhance hole generation, injection, and transfer, and using specific compounds in the organic material layer to improve charge injection and transfer characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic electron acceptor compounds with strong electron withdrawing groups are used to enhance hole generation and injection, then hole injection efficiency is improved, but miscibility with hole transporting compounds decreases leading to poor charge transfer characteristics
Solution Approach 1:
The patent introduces a gradient doping concentration of organic electron acceptor compounds in the hole injection layer, with higher concentration near the anode and lower concentration toward the hole transport layer. This local variation in composition optimizes hole generation at the anode interface while maintaining compatibility with the hole transporting compound at the interface, thus resolving the contradiction between hole injection efficiency and miscibility.
Solution Approach 2:
The patent changes the concentration parameter of organic electron acceptor compounds spatially within the hole injection layer. By controlling the doping concentration gradient, the patent achieves both efficient hole generation (requiring high acceptor concentration) and good miscibility with hole transporting compounds (requiring low acceptor concentration), thereby resolving the technical contradiction.
2Productivity
If high concentration of organic electron acceptor compounds is used to improve charge injection, then hole generation increases, but driving voltage increases due to poor charge transfer characteristics
Solution Approach 1:
The gradient doping profile concentrates organic electron acceptor compounds where they are most needed (near the anode for hole generation) while reducing concentration where they cause problems (near the hole transport layer where poor miscibility increases driving voltage). This local optimization resolves the contradiction between charge injection efficiency and driving voltage.
Solution Approach 2:
Instead of uniformly distributing organic electron acceptor compounds throughout the hole injection layer, the patent applies them partially and selectively in a gradient manner, achieving sufficient hole generation without the excessive concentration that would lead to poor charge transfer and high driving voltage.
3Productivity
If organic electron acceptor compounds are doped into hole injection layer to enhance hole transfer, then luminous efficiency improves, but lifespan decreases due to crystallization from Joule heating
Solution Approach 1:
The gradient doping concentration optimizes the balance between luminous efficiency and lifespan by maintaining higher acceptor concentration where it enhances efficiency without excessive Joule heating, and lower concentration where thermal effects are more problematic, thus extending device lifespan while maintaining high luminous efficiency.
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 light emitting elements with high emission efficiency, long lifespan, and low driving voltage by optimizing hole and electron injection characteristics.
Implementation Method 1
it may withdraw electrons from a high occupied molecular orbital (HOMO) energy level of the adjacent hole transport layer to a low occupied molecular orbital (LUMO) energy level of the organic electron acceptor compound to generate holes
Implementation Method 2
organic light emission refers to a phenomenon in which electric energy is converted into light energy by an organic material
Data Source
AI summary
Embodiments of the present disclosure relate to an organic light emitting element and a display device. Specifically, there may be provided an organic light emitting element including a first compound represented by chemical formula 1 and a second compound represented by chemical formula 2 to provide excellent efficiency, long lifespan or low driving voltage and a display device including the organic light emitting element.