Buffer Bilayers for OLEDs Using Conductive Polymers and Nanoparticles
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Solution Overview
Problem
There is a need for improved buffer layers in organic electronic devices, particularly in OLEDs, as existing buffer layers with low conductivity and limited charge transport properties hinder the efficiency and longevity of these devices.
Innovation Solution
A buffer bilayer comprising a first layer of electrically conductive polymer doped with non-highly-fluorinated acid polymer and highly-fluorinated acid polymer, combined with a second layer of inorganic nanoparticles, such as oxides or sulfides, to enhance conductivity and charge transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single buffer layer with low conductivity is used, then the device structure is simple, but the charge transport efficiency is poor
Solution Approach 1:
The buffer layer is divided into two distinct layers: a first buffer layer in direct contact with the anode and a second buffer layer adjacent to the electroluminescent material. This segmentation allows each layer to be optimized for different functions - the first layer provides good adhesion and initial charge injection, while the second layer provides enhanced charge transport to the EL material, thereby resolving the contradiction between structural simplicity and charge transport efficiency.
Solution Approach 2:
The patent employs composite material strategies by combining different polymer materials with specific conductivity ranges in each buffer layer. The first buffer layer uses materials with conductivity of 10^-5 to 10^-8 S/cm, while the second layer uses materials with conductivity of 10^-3 to 10^-6 S/cm. This composite approach enables the buffer structure to achieve superior overall charge transport efficiency while maintaining manageable structural complexity.
2Ease of manufacture
If the buffer layer surface is not wettable, then the coating process is difficult, but the existing buffer layers have poor surface wettability
Solution Approach 1:
The patent applies local quality by optimizing the surface properties of the first buffer layer specifically for wettability. The first buffer layer, being in direct contact with the anode and serving as the bottom interface, is designed with materials and properties that enhance surface wettability, facilitating easy coating of subsequent layers. This localized optimization of surface properties resolves the contradiction between ease of manufacture and surface wettability without compromising the overall device performance.
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 buffer bilayer improves the conductivity and charge transport properties, leading to increased efficiency and longevity of organic electronic devices, while also making the surface more wettable for easier coating, thus facilitating industrial-scale processing.
Implementation Method 1
at least one electrically conductive polymer doped with at least one non-highly-fluorinated acid polymer, and at least one highly-fluorinated acid polymer
Implementation Method 2
a second layer in contact with the first layer, the second layer comprising inorganic nanoparticles selected from the group consisting of oxides, sulfides, and combinations thereof
Implementation Method 3
at least one highly-fluorinated acid polymer
Data Source
AI summary
The present invention relates to buffer bilayers, and their use in electronic devices. The bilayer has a first layer including (a) at least one electrically conductive polymer doped with at least one non-highly-fluorinated acid polymer and (b) at least one highly-fluorinated acid polymer, and a second layer including inorganic nanoparticles which are oxides or sulfides.