Optical Mask With Spatially Varying Absorptivity
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Solution Overview
Problem
Conventional optical masks with photothermal conversion layers exhibit irregular thermal energy distribution, leading to non-uniform patterning and thin or uneven organic material layers due to Gaussian tails in the temperature profile, which affects the transfer of organic layers in organic light-emitting display devices.
Innovation Solution
An optical mask with a photothermal conversion pattern layer featuring alternating high- and low-absorptivity regions, where high-absorptivity regions cover the edges and low-absorptivity regions cover the center, providing a more uniform temperature distribution and preventing Gaussian tails, thereby improving the transfer profile of organic material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional photothermal conversion layer with uniform absorptivity is used, then the layer structure is simple, but the temperature distribution becomes non-uniform due to Gaussian tails, resulting in poor patterning uniformity
Solution Approach 1:
The photothermal conversion layer is divided into regions with different light absorptivity values. First regions have a first light absorptivity and second regions have a second light absorptivity, where the second light absorptivity is greater than the first light absorptivity. This local differentiation of absorptivity properties compensates for the Gaussian temperature profile, achieving uniform temperature distribution and improved patterning uniformity across the substrate.
2Temperature
If high-absorptivity regions are used throughout the photothermal conversion layer, then more thermal energy is generated, but the temperature distribution becomes non-uniform with Gaussian tails, causing uneven organic layer transfer
Solution Approach 1:
Different regions of the photothermal conversion layer are assigned different absorptivity values based on their position. Second regions (typically at edges or periphery) have higher absorptivity to generate more heat where the Gaussian profile causes temperature loss, while first regions (typically at center) have lower absorptivity. This spatially varying absorptivity redistributes thermal energy generation to achieve uniform temperature across the layer.
3Manufacturing precision
If a single-layer photothermal conversion structure is used, then the device is easier to manufacture, but the temperature profile shows Gaussian tails leading to thin and uneven organic material layers
Solution Approach 1:
The light absorptivity parameter of the photothermal conversion layer is varied spatially across different regions. By changing the absorptivity parameter from a uniform value to a gradient or stepped distribution (with first regions having lower absorptivity and second regions having higher absorptivity), the temperature profile is flattened to eliminate Gaussian tails, ensuring uniform organic material layer thickness during transfer.
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 uniform temperature distribution across the photothermal conversion pattern layer ensures a more consistent and efficient transfer of organic material layers, addressing the issues of non-uniformity and thinness associated with conventional masks, resulting in improved patterning and layer thickness.
Implementation Method 1
The photothermal conversion pattern layer includes first regions with a first light absorptivity and second regions with a second light absorptivity, wherein the second light absorptivity is greater than the first light absorptivity
Data Source
AI summary
An optical mask including a transmissive base substrate, a reflective pattern layer, and a photothermal conversion pattern layer. The reflective pattern layer is disposed on the transmissive base substrate. The reflective pattern layer includes reflectors. The photothermal conversion pattern layer is disposed on the transmissive base substrate among the reflectors. The photothermal conversion pattern layer includes first regions with a first light absorptivity and second regions with a second light absorptivity. The second light absorptivity is greater than the first light absorptivity. The first regions are disposed among the second regions.