OLED Transistor Structure Optimization for Emission Efficiency
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Solution Overview
Problem
Active matrix OLED display devices face a decrease in emitting efficiency due to switching and driving transistors being fabricated with the same structure, which cannot adequately fulfill their different roles, leading to inefficiencies in both manufacturing and emitting processes.
Innovation Solution
Designing and manufacturing switching and driving transistors with different configurations, using polycrystalline silicon (poly-Si) semiconductor layers for both, with distinct gate and source/drain electrode structures, and incorporating amorphous silicon doped ohmic contact layers to enhance their specific functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switching and driving transistors are fabricated with the same structure, then manufacturing process efficiency is maintained, but emitting efficiency decreases due to inability to fulfill different roles adequately
Solution Approach 1:
The patent applies different transistor structures to different functional requirements: the switching transistor uses an inverted staggered structure optimized for low leakage current, while the driving transistor uses a staggered structure optimized for high drivability. This local differentiation allows each transistor to perform its specific role effectively without compromising overall manufacturing efficiency.
Solution Approach 2:
The pixel is segmented into two distinct transistor structures with different configurations. The switching transistor and driving transistor are fabricated separately with optimized structures for their respective functions, rather than using a uniform structure for both, thereby resolving the contradiction between manufacturing simplicity and functional performance.
2Object-generated harmful factors
If switching transistor uses inverted staggered structure, then leakage current is reduced, but manufacturing complexity increases
Solution Approach 1:
The inverted staggered structure is applied specifically to the switching transistor where low leakage current is critical, while the driving transistor uses a simpler staggered structure. This localized application of complex structure only where needed minimizes overall device complexity while achieving the desired low leakage performance.
3Power
If driving transistor uses staggered structure, then drivability is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The staggered structure with enhanced drivability is applied specifically to the driving transistor, while the switching transistor uses the inverted staggered structure. This localized optimization allows high drivability where needed without imposing the same manufacturing precision requirements on the entire pixel structure.
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 approach improves emitting efficiency by optimizing the roles of switching and driving transistors, maintaining high manufacturing process efficiency while ensuring low leakage current and high drivability, thus enhancing the overall performance of OLED display devices.
Implementation Method 1
An OLED display device is a display device emitting light with a specific wavelength using energy generated from excitons generated by recombining electrons and holes
Implementation Method 2
an a-Si layer is typically formed on a substrate and crystallized by one of solid phase crystallization (SPC), rapid thermal annealing (RTA), metal induced crystallization (MIC), metal induced lateral crystallization (MILC), excimer laser annealing (ELA), and sequential lateral solidification (SLS)
Data Source
AI summary
An organic light emitting diode (OLED) display device and a method of fabricating the same are disclosed. The OLED display device includes a plurality of scan lines, a plurality of data lines, and a plurality of pixels disposed in a region in which the scan lines cross the data lines, where each pixel of the plurality of pixels includes: a switching transistor including a first gate electrode, a first semiconductor layer disposed over the first gate electrode, a first gate insulating layer interposed between the first gate electrode and the first semiconductor layer, a first source electrode and a first drain electrode, a driving transistor including a second semiconductor layer, a second gate electrode disposed over the second semiconductor layer, a second gate insulating layer interposed between the second gate electrode and the second semiconductor layer, a second source electrode and a second drain electrode, and an organic light emitting diode electrically connected with the second source and second drain electrodes of the driving transistor, where the first and second semiconductor layers are formed of the same material, and from the same processing.