Tandem OLED Intermediate Layer Segmentation for Voltage Reduction
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving high convenience, usefulness, and reliability due to limitations in electron-injection and transport properties, leading to increased driving voltage and power consumption.
Innovation Solution
A display apparatus comprising a first and second light-emitting device, each with specific layers and materials that facilitate electron injection and transport, including organic compounds with halogen or cyano groups, transition metal oxides, and a charge-generation layer to reduce current flow and prevent unintended light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electron-injection layers are used, then device structure is simple, but electron-injection and transport properties are insufficient leading to high driving voltage
Solution Approach 1:
The intermediate layer is divided into multiple functional layers: a first layer containing an organic compound with electron-withdrawing groups (halogen, cyano, or transition metal oxide) for hole injection, and a second layer containing an organic compound with electron-injection property for electron injection. This segmentation allows each layer to specialize in specific charge transport functions, improving overall electron-injection and transport properties while reducing driving voltage.
Solution Approach 2:
The invention uses composite material structures where the first layer contains organic compounds with electron-withdrawing groups (such as halogen groups, cyano groups, or transition metal oxides) combined with hole-transport materials, and the second layer contains organic compounds with electron-injection properties. This composite approach creates synergistic effects that enhance both hole and electron injection capabilities, addressing the insufficient charge transport properties of conventional single-material layers.
2Use of energy by stationary object
If conventional electron-transport materials are used, then manufacturing process is simple, but electron-transport property is insufficient leading to high power consumption
Solution Approach 1:
The electron-transport function is segmented into two specialized layers: the first layer handles hole transport using organic compounds with electron-withdrawing groups, and the second layer handles electron injection using organic compounds with electron-injection properties. This segmentation optimizes the transport properties for each charge carrier type, reducing the overall power consumption by improving charge injection efficiency.
Solution Approach 2:
The invention changes the chemical parameters of the materials by selecting organic compounds with specific electron-withdrawing groups (halogen, cyano, transition metal oxide) in the first layer and organic compounds with electron-injection properties in the second layer. This parameter optimization enhances the electron-transport capability and reduces the voltage required for operation, thereby lowering power consumption.
3Area of stationary object
If adjacent light-emitting devices are placed close together, then display area is maximized, but unintended light emission occurs due to current flow between devices
Solution Approach 1:
The region between the first and second intermediate layers of adjacent light-emitting devices serves as an intermediary barrier. This region, which overlaps with the gap between electrodes, prevents direct current flow between adjacent devices while allowing the devices to be positioned close together for maximum display area utilization.
Solution Approach 2:
The intermediate layers are designed with different local qualities: the first layer has properties optimized for hole injection and transport, while the second layer has properties optimized for electron injection. This local differentiation creates effective charge management at the interfaces between adjacent devices, preventing unintended light emission while maintaining high display area density.
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 solution enables a display apparatus with low driving voltage, low power consumption, and improved reliability, providing a novel and convenient electronic device.
Implementation Method 1
The first layer contains an organic compound having a halogen group or a cyano group or a transition metal oxide
Implementation Method 2
The second layer contains an organic compound exhibiting an electron-injection property
Implementation Method 3
The first intermediate layer and the second intermediate layer are separated from each other by the region, and the region overlaps with the gap
Data Source
AI summary
A novel display apparatus that is highly convenient, useful, or reliable is provided. The display apparatus includes a first tandem light-emitting device and a second tandem light-emitting device. The first tandem light-emitting device includes a first intermediate layer, the second tandem light-emitting device is adjacent to the first tandem light-emitting device, and the second tandem light-emitting device includes a second intermediate layer. A gap is included between the second intermediate layer and the first intermediate layer, the second intermediate layer contains an organic compound exhibiting an electron-injection property, and the organic compound exhibiting an electron-injection property is represented by General Formula (G0). Note that A is a substituted or unsubstituted aryl skeleton having 6 to 30 carbon atoms or a substituted or unsubstituted heteroaryl skeleton having 2 to 30 carbon atoms, and n is an integer greater than or equal to 1 and less than or equal to 4.