OLED Electrode Structure with Patterned Conductive Layer
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Solution Overview
Problem
In organic light-emitting diode (OLED) devices, the impedance of transparent electrodes increases with size, leading to non-uniform light emission and potential short circuits due to the rough surface of auxiliary electrodes formed by printing processes, which affects the device's efficiency and lifespan.
Innovation Solution
A light emitting device structure comprising a substrate with a first transparent conductive layer, a patterned conductive layer, and a second transparent conductive layer, where the patterned conductive layer is interposed between the first and second transparent conductive layers to reduce impedance and prevent short circuits, with the second transparent conductive layer covering the patterned layer to smooth the surface and ensure uniform light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the area of OLED device is increased, then the light emitting area is increased, but the impedance of transparent electrode increases leading to non-uniform light emission
Solution Approach 1:
The transparent electrode is divided into multiple segments: a first transparent electrode, a second transparent electrode, and an auxiliary transparent electrode. This segmentation allows each electrode to have optimized dimensions and conductivity distribution, reducing overall impedance while maintaining large light emitting area and ensuring uniform light emission across the device.
Solution Approach 2:
The auxiliary transparent electrode is positioned at specific locations (such as at least one end of the first transparent electrode) to locally enhance conductivity where needed. This creates non-uniform conductivity distribution that compensates for impedance variations across the large area device, ensuring uniform light emission without requiring the entire electrode structure to have high conductivity.
2Reliability
If an auxiliary electrode is formed by printing process, then the impedance is reduced, but the surface becomes rough causing light emitting layer cracks and short circuits
Solution Approach 1:
A buffer layer is introduced as an intermediary between the auxiliary transparent electrode and the light emitting layer. This buffer layer has a first refractive index different from the auxiliary electrode's refractive index, creating an optical and physical buffer that prevents direct contact between the rough electrode surface and the light emitting layer, thereby preventing cracks and short circuits while maintaining the electrode's conductivity benefits.
Solution Approach 2:
The electrode structure employs composite material design with multiple transparent electrode materials having different properties. The auxiliary transparent electrode can be made from materials optimized for conductivity, while the buffer layer uses materials optimized for surface smoothness and optical properties, creating a composite structure that achieves both low impedance and high manufacturing precision.
3Reliability
If an insulator layer is added on auxiliary electrode, then short circuit is prevented, but the device complexity increases
Solution Approach 1:
The buffer layer serves multiple functions simultaneously: it acts as an insulator to prevent short circuits between the auxiliary electrode and light emitting layer, provides optical matching through refractive index control to maintain light emission efficiency, and offers mechanical protection against surface roughness. This multi-functionality prevents the need for separate insulator layers, reducing overall device complexity while achieving short circuit prevention.
Data Source
AI summary
A light emitting device including a substrate, a first electrode structure, an organic light emitting structure and a second electrode structure is provided. The first electrode structure includes a first transparent conductive layer, a patterned conductive layer and a second transparent conductive layer disposed on the substrate in sequence, so that the patterned conductive layer is interposed between the second transparent conductive layer and the first transparent conductive layer in a thickness direction of the substrate. The organic light emitting structure and the second electrode structure are disposed on the substrate, and the organic light emitting structure is located between the first electrode structure and the second electrode structure in the thickness direction of the substrate. An electrode structure and a manufacturing method thereof are also provided.