Organic OLED Emission Layer Structure for Hole Trap Balance
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Solution Overview
Problem
Existing organic optoelectronic devices face challenges in achieving high efficiency, low driving voltage, and long lifespan.
Innovation Solution
The device incorporates a specific layer structure with a first and second light emitting layer, each containing a host and dopant combination, including an iridium complex and a platinum complex, and calculates the hole trap index to optimize the light emitting zone towards the anode, using compounds like N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine and N-([1,1'-biphenyl]-4-yl)-N-(2-(9,9-diphenyl-9H-fluoren-4-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-amine, to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional single light emitting layer structure is used, then the device structure is simple, but the efficiency and lifespan are insufficient
Solution Approach 1:
The device divides the light emitting layer into two distinct layers: a first light emitting layer containing a first host compound and first dopant, and a second light emitting layer containing a second host compound and second dopant. This segmentation allows each layer to be optimized for specific functions, improving overall device efficiency while managing complexity through modular design
Solution Approach 2:
Each light emitting layer is assigned different local qualities through specific compound selections and dopant concentrations. The first light emitting layer uses an iridium complex dopant optimized for certain emission characteristics, while the second light emitting layer uses a platinum complex dopant with different properties, allowing localized optimization of emission efficiency and color characteristics
2Productivity
If high efficiency materials are used, then the device performance improves, but the driving voltage increases
Solution Approach 1:
The device optimizes multiple parameters including dopant concentration (1-10 wt%), host compound molecular weight ratios, and layer thicknesses to achieve the optimal balance between luminous efficiency and driving voltage. By carefully adjusting these parameters, the device achieves high efficiency without excessive voltage requirements
Solution Approach 2:
Each light emitting layer uses a composite material system combining specific host compounds with metal complex dopants. The first light emitting layer combines a first host compound with an iridium complex, while the second light emitting layer combines a second host compound with a platinum complex, creating composite materials that optimize both efficiency and electrical characteristics
3Speed
If the light emitting zone is positioned towards the cathode, then the electron transport is improved, but the hole transport becomes insufficient
Solution Approach 1:
The device segments the charge transport functions across two light emitting layers. The first light emitting layer is optimized for hole transport with appropriate host and dopant selection, while the second light emitting layer is optimized for electron transport. This segmentation ensures both charge carriers are efficiently transported to their respective zones, maintaining charge balance
Solution Approach 2:
The interface between the two light emitting layers acts as an intermediary zone that facilitates balanced charge transport. The specific combination of host compounds and dopants in each layer creates energy level alignments that enable smooth charge transfer across the interface, ensuring both holes and electrons are properly transported
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 results in a high-efficiency, low-driving voltage, and long-lasting organic optoelectronic device.
Implementation Method 1
the first dopant is an iridium complex and the second dopant is a platinum complex
Data Source
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AI summary
Provided is an organic optoelectronic device and display device including an anode and a cathode facing each other, an intermediate layer between the anode and the cathode, wherein the intermediate layer includes a first light emitting layer and a second light emitting layer, the first light emitting layer is disposed between an anode and a second light emitting layer, and includes a first host including a composition of a first compound and a second compound, and a first dopant, the second light emitting layer is disposed between the cathode and the first light emitting layer, and includes a second host including a composition of a third compound and a fourth compound and a second dopant, the first dopant is an iridium complex and the second dopant is a platinum complex, and the organic optoelectronic device satisfies Formula 1: hole trap index of the first light emitting layer > hole trap index of the second light emitting layer The hole trap index is calculated according to Formula 2: hole trap index = [1 - {(current density measured at 7 V voltage after doping the dopant in the light emitting layer in HOD (Hole Only Device))/(current density measured at 7 V voltage before doping the dopant in the light emitting layer in HOD (Hole Only Device))}] * 100, HOD: ITO/Compound E (1,400 Å)/Compound F (1% NDP-9 doping, 100 Å)/Compound F (200 Å)/light emitting layer (400 Å)/ HAT-CN (100 Å) / Ag (50 Å) / Mg:Ag (9:1, 550 Å); Compound E: N-([1,1'-biphenyl]-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine; and Compound F: N-([1,1'-biphenyl]-4-yl)-N-(2-(9,9-diphenyl-9H-fluoren-4-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-amine).