OLED Display Amorphous Silicon TFT Electron Injection Dipole Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing OLED display technologies face challenges in increasing display size due to the complex manufacturing process of low temperature polycrystalline silicon thin film transistors (LTPS TFTs), which affects productivity as the size of the display increases, and amorphous silicon TFTs lack efficient electron injection capabilities.
Innovation Solution
The OLED display incorporates an amorphous silicon thin film transistor with a structured organic light emitting diode configuration, including a transparent electrode with a work function greater than 4.5 eV, a reflective electrode with a work function lower than 4.5 eV, and specifically designed electron and hole injection units with metal layers and dipole layers for improved electron and hole injection, enabling effective rear emission type displays suitable for large-area processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low temperature polycrystalline silicon thin film transistor (LTPS TFT) is used to achieve excellent carrier mobility, then device performance is improved, but manufacturing process complexity increases and productivity deteriorates as display size increases
Solution Approach 1:
The patent changes the transistor type from LTPS TFT to amorphous silicon TFT, which eliminates the need for complex crystallization processes while maintaining functional performance through optimized OLED electrode structures with specific work function parameters (>4.5 eV for transparent electrode, <4.5 eV for reflective electrode)
Solution Approach 2:
The patent introduces an intermediary electron injection layer with dipole characteristics between the amorphous silicon TFT and the organic emission layer, which enables effective electron injection from the amorphous silicon transistor without requiring complex LTPS processing
2Productivity
If amorphous silicon TFT is used to simplify manufacturing process and enable large-area processing, then productivity is improved, but electron injection capability into organic emission layer deteriorates
Solution Approach 1:
The patent introduces an electron injection layer with dipole characteristics as an intermediary between the amorphous silicon TFT and the organic emission layer. This dipole layer has electron affinity greater than 2.5 eV and creates a favorable energy level alignment that enables effective electron injection from amorphous silicon without requiring complex crystallization processes
Solution Approach 2:
The patent optimizes the work function parameters of the electrodes (transparent electrode >4.5 eV, reflective electrode <4.5 eV) and the electron affinity of the injection layer (>2.5 eV) to create favorable energy level alignment that compensates for the lower electron mobility of amorphous silicon, enabling effective electron injection
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
This configuration enhances the size scalability of OLED displays by improving electron and hole injection efficiency, maintaining or exceeding the characteristics of typical rear emission type OLEDs, and preventing damage to the organic emission layer during processing, thus achieving effective large-area display capabilities.
Implementation Method 1
a transparent electrode connected with the thin film transistor and being capable of injecting electrons
Implementation Method 2
Electrons and holes are combined with each other in an organic emissive layer to thereby generate excitons. When the excitons shift from the excited state to the ground state, energy is generated so as to emit light
Implementation Method 3
a reflective electrode on the organic emission layer and being capable of injecting holes
Implementation Method 4
the electron injection dipole layer having an electron affinity greater than about 2.5 eV
Implementation Method 5
Electrons and holes are combined with each other in an organic emissive layer to thereby generate excitons. When the excitons shift from the excited state to the ground state, energy is generated so as to emit light
Data Source
AI summary
An organic light emitting diode (OLED) display including a substrate main body; a thin film transistor on the substrate main body; and an organic light emitting diode including a transparent electrode connected with the thin film transistor and being capable of injecting electrons, an organic emission layer on the transparent electrode, and a reflective electrode on the organic emission layer and being capable of injecting holes, wherein the organic emission layer includes an electron injection unit on the transparent electrode, the electron injection unit including an electron injection metal layer, an electron injection layer, and an electron injection dipole layer, and a light emitting unit on the electron injection unit.