Organic Photodiode Array with Bulk Heterojunction and Moisture Barrier
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Solution Overview
Problem
Designing and manufacturing digital imaging arrays with organic semiconductor-based organic photodiodes (OPDs) for medical, industrial, and homeland security applications poses challenges due to the need for tailored spectral sensitivity, low intrinsic stress, and integration with flexible substrates, while existing methods are complex and costly.
Innovation Solution
An enhanced high-performance active matrix photosensor array design featuring a multilayer structure with a substrate, thin film transistor, single-layer or two-layer organic photodiode, bias connection, and barrier layer, utilizing a bulk heterojunction layer, hole transport layer, and top contact layer, with a moisture barrier to mitigate degradation, and employing screen printing or slot-die coating techniques for manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional multilayer organic photodiode structures are used, then device performance is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates unnecessary intermediate layers from the traditional multilayer organic photodiode structure. Specifically, it removes the separate electron transport layer and hole injection layer, retaining only the essential bulk heterojunction layer and top contact layer, thereby simplifying the manufacturing process while preserving core device functionality.
Solution Approach 2:
The patent merges multiple functional layers into a simplified architecture. The bulk heterojunction layer combines light absorption, exciton generation, and charge separation functions, while the top contact layer integrates both electron and hole transport capabilities, reducing the total number of layers required for device operation.
2Reliability
If multiple protective layers are added to prevent degradation, then device stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent employs a thin film moisture barrier layer as a flexible protective shell that prevents degradation from environmental moisture. This single thin film layer provides sufficient protection without requiring multiple thick protective layers, maintaining device stability while minimizing structural complexity.
3Productivity
If conventional manufacturing techniques are used, then manufacturing precision is maintained, but productivity and cost-effectiveness decrease
Solution Approach 1:
The patent replaces complex mechanical layer-by-layer deposition techniques with solution-based printing methods. The simplified two-layer structure can be fabricated using inkjet printing, screen printing, or slot-die coating, which are higher throughput techniques that maintain adequate precision for organic photodiode applications without requiring ultra-precise mechanical control.
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 simplifies the manufacturing process, reduces costs, and improves performance by eliminating unnecessary layers, enhancing light sensitivity and responsiveness, while maintaining low leakage and scalability up to large areas, suitable for applications like X-ray and IR sensors.
Implementation Method 1
a bulk heterojunction layer directly coupled to a top layer of the stacked metal layer... wherein the bulk heterojunction layer can comprise an electron donor/acceptor material
Implementation Method 2
a hole transport layer directly coupled to the bulk heterojunction layer... wherein the hole transport layer can comprise a conductive polymer material
Data Source
AI summary
An image sensor includes a substrate, a thin film transistor on the substrate, a dielectric layer over the thin film transistor, a stacked metal layer on and extending through the dielectric layer to the thin film transistor, a bulk heterojunction layer directly coupled to the stacked metal layer, either a hole transport layer directly coupled to the bulk heterojunction layer, and a top contact layer directly coupled to the hole transport layer, or a top contact layer directly coupled to the bulk heterojunction layer. The bulk heterojunction layer includes an electron donor/acceptor material, the hole transport layer includes a transparent conductive polymer material, and the top contact layer includes a transparent conductive material. The image sensor includes a moisture barrier layer directly coupled to the top contact layer, including an optically clear adhesive and a laminated transparent barrier film.