OLED Anode Structure with Diffusion Barrier
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Solution Overview
Problem
Existing anode structures in organic light emitting diode (OLED) display devices face challenges in achieving high reflective efficiency and maintaining excellent electrical characteristics, particularly in preventing metal diffusion between layers which affects work function and surface uniformity, and in suppressing leakage currents.
Innovation Solution
An anode structure is designed with a diffusion barrier layer pattern, such as titanium nitride, interposed between a first metal layer pattern, like an aluminum-copper alloy, and a second metal layer pattern, like cobalt, to prevent metal diffusion and enhance reflective efficiency, along with a leakage current suppressing layer pattern to manage electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a first metal layer pattern (aluminum-copper alloy) is used to upwardly reflect light, then reflective efficiency is improved, but metal diffusion occurs between layers affecting work function and surface uniformity
Solution Approach 1:
A diffusion barrier layer pattern (titanium nitride) is introduced as an intermediary between the first metal layer pattern (aluminum-copper alloy) and the second metal layer pattern (cobalt). This intermediate layer prevents direct contact between the metal layers, blocking diffusion of metal atoms while maintaining the reflective properties of the first metal layer and the electrical characteristics of the second metal layer.
Solution Approach 2:
The anode structure employs a composite multi-layer configuration combining aluminum-copper alloy (for high reflectivity), titanium nitride (for diffusion barrier properties), and cobalt (for work function control). Each material is selected for its specific properties, and their combination creates a structure that simultaneously achieves high reflective efficiency, prevents metal diffusion, and maintains excellent electrical characteristics.
2Device complexity
If metal layers are directly contacted to simplify structure, then device complexity is reduced, but leakage currents increase due to electric field concentration
Solution Approach 1:
The diffusion barrier layer pattern serves as a mediator not only preventing metal diffusion but also acting as an isolation layer that reduces electric field concentration at metal layer interfaces. This intermediary structure suppresses leakage currents while adding minimal complexity to the overall device architecture.
3Reliability
If a second metal layer pattern with high work function (4.0 eV or more) is applied to improve electrical characteristics, then anode current and hole-electron recombination are enhanced, but work function loss occurs due to metal diffusion
Solution Approach 1:
The titanium nitride diffusion barrier layer pattern is positioned between the aluminum-copper alloy layer and the cobalt layer to prevent diffusion of aluminum or copper atoms into the cobalt layer. This protection maintains the high work function (4.0 eV or more) of the cobalt layer, ensuring stable electrical characteristics including anode current and hole-electron recombination properties throughout device operation.
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 solution effectively suppresses work function loss, maintains surface uniformity of the second metal layer, and reduces leakage currents, thereby improving the overall performance of the OLED display device by enhancing light reflection and electrical characteristics.
Implementation Method 1
a first metal layer pattern disposed on the insulating interlayer, comprising a first metal configured to upwardly reflect light emitted from an organic light emitting unit
Implementation Method 2
a diffusion barrier layer pattern interposed between the first metal layer pattern and the second metal layer pattern for preventing elements of the first metal or the second metal from diffusing between the first metal layer and the second metal layer
Data Source
AI summary
An anode structure of an organic light emitting diode display device, includes an insulating interlayer disposed on a silicon substrate, a first metal layer pattern disposed on the insulating interlayer comprising a first metal to be configured to upwardly reflect light, a second metal layer pattern formed on the first metal layer pattern comprising a second metal having a work function of 4.0 eV or more, and a diffusion barrier layer pattern interposed between the first metal layer pattern and the second metal layer pattern for preventing elements of the first metal or the second metal from diffusing between the first metal layer and the second metal layer.