OLED Display Panel Auxiliary Light Emitting Layer Electron Transport
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Solution Overview
Problem
Existing OLED display devices face limitations in electron transport efficiency due to the disparity between electron and hole mobility, leading to suboptimal luminous efficiency and increased voltage requirements.
Innovation Solution
Incorporating a first auxiliary light emitting layer with a host material containing a pyridyl group and a rare earth metal element, which expands the electron transport region through conjugated π-bond electron clouds, balancing electron and hole transport rates and improving device stability with a glass transition temperature of 90° C or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electron transport materials are used, then the device structure is simple, but the electron transport rate is much smaller than the hole transport rate, leading to low luminous efficiency and high voltage
Solution Approach 1:
The patent uses a composite material system consisting of a host material (containing pyridyl group and conjugated aromatic group) doped with a metal element. This composite structure combines the electron-accepting capability of the pyridyl group with the electron cloud delocalization of conjugated aromatic groups and the catalytic effect of metal elements, achieving balanced electron and hole transport rates while maintaining device structure simplicity
Solution Approach 2:
The patent changes the chemical and physical parameters of the electron transport layer by selecting a host material with specific structural features (pyridyl group with conjugated aromatic group) and controlling the doping concentration of metal elements. This parameter optimization enables the electron transport rate to match the hole transport rate, thereby improving luminous efficiency without complicating the device structure
2Productivity
If the electron transport rate is improved by using conventional materials, then the luminous efficiency increases, but the voltage remains high due to unbalanced charge transport
Solution Approach 1:
The patent optimizes the chemical structure parameters of the host material (incorporating pyridyl group with conjugated aromatic group) and controls the metal element doping concentration to achieve balanced charge transport. This parameter optimization simultaneously improves luminous efficiency and reduces operational voltage by eliminating the charge transport imbalance that previously required higher voltage compensation
3Speed
If the host material structure is optimized to improve electron transport, then the electron mobility increases, but the glass transition temperature may decrease, affecting device stability
Solution Approach 1:
The patent carefully selects and optimizes the host material structure (pyridyl group with specific conjugated aromatic groups) and metal element doping concentration to achieve the right balance between electron mobility and glass transition temperature. The conjugated aromatic groups provide electron delocalization for high mobility while the overall molecular structure maintains sufficient thermal stability with Tg ≥90° C.
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 approach enhances luminous efficiency, extends the device's lifetime, reduces operational voltage, and stabilizes the OLED panel by ensuring better electron injection and transport, while maintaining film forming properties and preventing crystallization during coating.
Implementation Method 1
the occurring region of electrons of the bonded metal element can be expanded by the nitrogen element contained therein and the formed conjugated π-bond electron cloud, thereby improving the transport rate of electrons
Implementation Method 2
a specific host doping material is selected and doped with a metal element in a way of host-guest doping to obtain an electron-type auxiliary light emitting layer with a balanced electron transport rate and hole transport rate
Data Source
AI summary
The present disclosure relates to an OLED display panel, comprising a first electrode and a second electrode, a light emitting layer and a first auxiliary light emitting layer disposed between the first electrode and the second electrode, the first auxiliary light emitting layer is disposed between the light emitting layer and the second electrode, wherein the first auxiliary light emitting layer includes at least a first electron-type auxiliary light emitting layer, wherein the first electron-type auxiliary light emitting layer includes a host material and a metal element doped in the host material; the host material has at least one pyridyl group and an aromatic group conjugated to the at least one pyridyl group; and the glass transition temperature of the host material is ≥90° C. The present disclosure can improve the luminous efficiency and lifetime of an organic photoelectronic device and reduce its voltage by using this method.