Organic Electroluminescent Device with Dual-Host Red Emission
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Solution Overview
Problem
Existing OLED display devices exhibit inconsistent turn-on voltages among RGB sub-pixels, particularly with the blue sub-pixel having a higher turn-on voltage and lower luminous efficiency at low-voltage, leading to color reddening and crosstalk due to inefficiencies in the red and green sub-pixels.
Innovation Solution
An organic electroluminescent device with a specific combination of arylamine derivative in the hole transport region and dual-host red-light material in the light emitting layer, utilizing a second hole transport layer material and host materials with defined structural formulas, to achieve a high turn-on voltage and low driving voltage, maintaining high efficiency and long service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dual-host red-light device is used, then luminous efficiency is improved, but turn-on voltage decreases leading to color reddening and crosstalk
Solution Approach 1:
The patent modifies the turn-on voltage parameter of the red sub-pixel by optimizing the host material structure (introducing specific substituents like CF3, F, Cl, Br, or NO2 groups) and adjusting the energy level alignment between host and dopant materials. This parameter change enables the red sub-pixel to achieve both high luminous efficiency and appropriate turn-on voltage, preventing color reddening and crosstalk while maintaining exciplex emission characteristics.
2Reliability
If a single-host red-light device is used, then turn-on voltage is improved, but luminous efficiency and service life decrease
Solution Approach 1:
The patent employs a dual-host material system comprising a first host material (with specific structural formulas containing electron-withdrawing groups) and a second host material, forming a composite material structure. This composite approach combines the advantages of both single-host and dual-host systems, achieving high turn-on voltage through optimized energy level alignment while maintaining high luminous efficiency and long service life through the synergistic effects of the dual-host exciplex emission mechanism.
3Use of energy by stationary object
If driving voltage is reduced, then power consumption is reduced, but red sub-pixel efficiency decreases causing color imbalance
Solution Approach 1:
The patent optimizes the energy level parameters of the host and dopant materials to achieve appropriate turn-on voltage (0.5-1.5V higher than green and blue sub-pixels). By carefully selecting host materials with specific HOMO/LUMO energy levels and dopant materials with matched energy levels, the red sub-pixel maintains high efficiency at low driving voltages, enabling power-efficient operation without color imbalance or crosstalk.
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 device alleviates color reddening by improving the turn-on voltage of the red-light device, retaining high efficiency and longevity while reducing driving voltage disparities among sub-pixels.
Implementation Method 1
Organic light-emitting diode (OLED) displays are active light-emitting display apparatuses
Data Source
AI summary
An organic electroluminescent device has a first electrode, a second electrode, which faces the first electrode, a light-emitting layer, which is located between the first electrode and the second electrode, and a hole transport region, which is located between the first electrode and the light-emitting layer. The hole transport region includes a hole injection layer, a first hole transport layer and a second hole transport layer. The organic electroluminescent device is manufactured by a specific combination of a specific arylamine derivative contained in a hole transport region and a dual-host red-light material contained in a light-emitting layer. The manufactured organic electroluminescent device has a high turning-on voltage and also has a relatively low driving voltage. Increasing the turning-on voltage of a red-light device reduces the phenomenon of the color displayed appears reddish caused by crosstalk.