Green OLED Electroluminescent Element with Composite Host Materials
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Solution Overview
Problem
Conventional electroluminescent elements, particularly in OLEDs, face issues with low green light luminous efficiency and short service life due to excessive triplet exciton annihilation and imbalanced exciton recombination regions.
Innovation Solution
The electroluminescent element is designed with a green light-emitting layer comprising a hole-type host material, an electron-type host material, and a green guest light-emitting material, where the mobility and energy level ratios are carefully adjusted to control the exciton recombination region, moving it from the edge towards the interior of the layer, thereby reducing triplet exciton annihilation and enhancing efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electroluminescent elements use traditional host materials and layer structures, then the device structure is simple and easy to manufacture, but the green light luminous efficiency is low and the service life is short
Solution Approach 1:
The patent uses composite host materials comprising both hole-transporting host material and electron-transporting host material in the light-emitting layer. This composite structure enables balanced charge transport, reduces exciton annihilation, and improves both luminous efficiency and device service life without significantly complicating the manufacturing process
Solution Approach 2:
The patent introduces different types of host materials with specific local functions (hole transport and electron transport) at different regions within the light-emitting layer. This local differentiation optimizes charge distribution and recombination zones, thereby extending device service life while maintaining manufacturability
2Ease of manufacture
If conventional electroluminescent elements use traditional host materials and layer structures, then the device structure is simple and easy to manufacture, but the green light luminous efficiency is low
Solution Approach 1:
The patent employs composite host materials with complementary charge transport properties to achieve balanced electron and hole injection into the light-emitting layer. This balance reduces non-radiative recombination and triplet exciton annihilation, significantly improving green light luminous efficiency while keeping the device structure relatively simple and manufacturable
Solution Approach 2:
The patent optimizes the ratio of hole-transporting to electron-transporting host materials and adjusts their energy levels and mobility parameters to achieve optimal charge balance. These parameter optimizations enhance luminous efficiency without requiring fundamental changes to the manufacturing process
3Device complexity
If the exciton recombination region is concentrated at the edge of the light-emitting layer, then the device structure is simple, but triplet exciton annihilation is excessive and reduces efficiency and lifespan
Solution Approach 1:
The patent creates localized regions with different charge transport properties within the light-emitting layer by using different host materials. This causes the exciton recombination region to shift from the edge to the interior of the layer, reducing triplet exciton annihilation and improving efficiency without significantly increasing device complexity
Solution Approach 2:
The electron-transporting host material acts as an intermediary that facilitates balanced charge distribution and shifts the recombination zone away from the edge. This intermediary function reduces harmful exciton annihilation while maintaining a relatively simple device 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
This configuration improves the luminous efficiency and extends the service life of the electroluminescent element by balancing hole and electron transport, weakening triplet exciton annihilation, and enlarging the exciton recombination region.
Implementation Method 1
holes generated by an anode and electrons generated by a cathode move to a light-emitting layer through a hole transport layer and an electron transport layer respectively
Implementation Method 2
When the holes and the electrons meet at the light-emitting layer, energy excitons are generated, so as to excite light-emitting molecules to finally generate visible light
Data Source
AI summary
The present disclosure provides an electroluminescent element, a display panel and a display device. The electroluminescent element includes an electron transport layer, a green light-emitting layer, and a hole transport layer laminated one on another. The green light-emitting layer includes a hole-type host material, an electron-type host material, and a green guest light-emitting material.