OLED EL Layer Structure for Low-Voltage Multi-Color Emission
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Solution Overview
Problem
Current light-emitting devices using organic compounds face challenges in reducing driving voltage and current consumption while maintaining high reliability and efficient emission characteristics.
Innovation Solution
A light-emitting device structure incorporating multiple EL layers with a charge-generation layer, where the EL layers contain specific organic compounds such as those with benzo[b]naphtho[1,2-d]furanylamine skeletons bonded to pyrene skeletons, enabling improved carrier balance and recombination probability, and utilizing phosphorescent substances for efficient light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional EL layer structures are used, then manufacturing simplicity is maintained, but driving voltage and current consumption cannot be reduced sufficiently
Solution Approach 1:
The EL layer is segmented into multiple distinct layers (first EL layer, second EL layer, third EL layer) with specific functional assignments. Each layer contains different organic compounds optimized for specific purposes: the first EL layer uses compounds with benzo[b]naphtho[1,2-d]furanylamine skeletons for high efficiency, the second EL layer uses phosphorescent substances for triplet exciton utilization, and the third EL layer provides additional emission control. This segmentation allows each layer to contribute to power reduction through specialized mechanisms.
Solution Approach 2:
The patent employs composite organic compound structures within the EL layers, specifically combining benzo[b]naphtho[1,2-d]furanylamine skeletons with pyrene skeletons in the first EL layer, and integrating phosphorescent substances in the second EL layer. These composite material structures enable simultaneous achievement of high emission efficiency and triplet exciton utilization, directly contributing to reduced power consumption while maintaining a manageable structural complexity through systematic material design.
2Use of energy by moving object
If driving voltage is reduced to lower power consumption, then energy efficiency improves, but emission characteristics and color purity may deteriorate
Solution Approach 1:
Different regions of the EL structure (first, second, and third EL layers) are assigned different material compositions and functional qualities. The first EL layer is optimized for high emission efficiency with benzo[b]naphtho[1,2-d]furanylamine compounds, the second EL layer is optimized for phosphorescent emission and triplet exciton utilization, and the third EL layer provides additional emission control. This local differentiation allows each layer to contribute to maintaining emission characteristics while the overall structure achieves lower driving voltage through cumulative efficiency improvements.
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 proposed structure achieves lower power consumption and high reliability with enhanced emission characteristics, allowing for effective reduction in driving voltage and current consumption while maintaining high color purity and efficiency.
Implementation Method 1
The light emission mechanism of a light-emitting element is said to be as follows: when a voltage is applied between a pair of electrodes with an EL layer including a luminous body provided therebetween, electrons injected from the cathode and holes injected from the anode recombine in the light emission center of the EL layer to form molecular excitons, and energy is released and light is emitted when the molecular excitons return to the ground state.
Implementation Method 2
The second EL layer has a function of emitting phosphorescence.
Data Source
AI summary
A light-emitting device, an electronic device, or a lighting device with low power consumption and high reliability is provided. The light-emitting device includes a first light-emitting element, a second light-emitting element, a third light-emitting element, and a fourth light-emitting element. The first to fourth light-emitting elements include the same EL layer between an anode and a cathode. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer contains a fluorescent substance. The peak wavelength of an emission spectrum of the fluorescent substance in a toluene solution of the fluorescent substance is 440 nm to 460 nm, preferably 440 nm to 455 nm. The second light-emitting layer contains a phosphorescent substance. The first light-emitting element exhibits blue emission. The second light-emitting element exhibits green emission. The third light-emitting element exhibits red emission. The fourth light-emitting element exhibits yellow emission.