OLED Encapsulation Using Composite Inorganic-Organic Barrier Layers
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Solution Overview
Problem
Organic light emitting diode (OLED) structures are susceptible to moisture and oxygen uptake, leading to performance degradation, necessitating effective encapsulation methods.
Innovation Solution
A method involving the formation of inorganic layers, tunable buffer layers with variable organic and inorganic components, and a capping inorganic layer, using processes like PECVD in a multi-chamber system with external mask alignment to achieve comprehensive encapsulation, ensuring a moisture and oxygen barrier while providing stress isolation and particle coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encapsulation layers are formed to protect OLED structures from moisture and oxygen, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent employs a composite encapsulation structure consisting of alternating inorganic layers (SiNx, SiOx, SiON, Al2O3) and organic buffer layers. This composite approach provides superior moisture and oxygen barrier properties compared to single-material encapsulation, while the organic buffer layers fill voids and defects in the inorganic layers to enhance overall protection effectiveness.
Solution Approach 2:
The encapsulation is divided into multiple discrete layers rather than using a single thick layer. The segmented structure includes bottom inorganic layer, organic buffer layer, intermediate inorganic layer, and top inorganic layer, each performing specific protective functions. This segmentation allows for better control of deposition processes and improved defect coverage.
2Manufacturing precision
If multiple process chambers are used for forming encapsulation layers, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The fabrication process is segmented into distinct process chambers: first process chamber for bottom inorganic layer, second process chamber for organic buffer layer, and third process chamber for intermediate and top inorganic layers. This segmentation allows each chamber to be optimized for specific material deposition requirements, ensuring precise control over layer quality and properties.
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 protects OLED structures from environmental degradation, maintaining performance by creating a robust barrier against moisture and oxygen while allowing for flexible and efficient fabrication processes.
Implementation Method 1
a tunable buffer layer can be fabricated by PECVD from a mixture of vaporized organic silicon compound such as hexamethyldisiloxane (HMDSO) or tetramethydiloxane (TMDSO) or similar organic silicon analogs
Implementation Method 2
it is necessary to provide an encapsulation, including alternating inorganic and organic thin film layers
Data Source
AI summary
A substrate includes a plurality of OLED, each having a conductor layer. A coating is formed over the OLEDs, the coating comprises a first inorganic layer formed over the OLED structures and at least partially over each of the contact layers, a buffer layer over the first inorganic layer, a second inorganic layer over the buffer layer, wherein the buffer layer comprises a first inorganic interface layer in contact with the first inorganic layer, a second inorganic interface layer in contact with the second inorganic layer, and an organic layer sandwiched between the first and second inorganic interface layers.