Organic Photodetector Bilayer Active Layer Sensitivity
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Solution Overview
Problem
Conventional photodetectors using silicon face challenges in sensitivity and integration as pixel sizes decrease, leading to deteriorated sensing sensitivity, prompting the need for alternative organic materials that can improve photodetection efficiency and integrate color filtering capabilities.
Innovation Solution
An organic photodetector design incorporating a bilayer active layer with p-type and n-type organic semiconductors, where the n-type semiconductor has a lower lowest unoccupied molecular orbital (LUMO) energy level than the p-type, and specific materials like boron subphthalocyanine chloride and C60 fullerene are used, along with a hole transport region and electron transport region to enhance exciton separation and quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon is used to implement photodiodes, then the device structure is simple and manufacturing is mature, but as pixel size decreases the absorption region decreases and sensing sensitivity is deteriorated
Solution Approach 1:
The patent changes the material parameter from silicon to organic materials with different optical properties. The organic materials have larger extinction coefficients and can be tuned to absorb light in specific wavelength regions, enabling high sensitivity photodetection in reduced absorption regions while maintaining or improving manufacturing precision through solution processing techniques
Solution Approach 2:
The patent employs composite organic semiconductor materials with specific HOMO and LUMO energy levels to create an active layer that combines high light absorption efficiency with effective charge separation. The composite material approach allows optimization of both optical absorption and electrical properties within a compact structure
2Measurement precision
If organic materials are used to replace silicon, then sensing sensitivity and high integration are improved, but the device structure becomes more complex with multiple layers required
Solution Approach 1:
The patent designs the organic photodetector structure to perform multiple functions: the active layer simultaneously provides light absorption, exciton generation, and charge separation; the energy level alignment between layers provides both charge separation and electron transport pathways. This multi-functionality reduces the need for additional separate components despite the layered structure
Solution Approach 2:
The patent applies local quality by creating specific regions with different material properties within the active layer. The first and second organic semiconductors are positioned to create localized regions for optimal exciton separation and charge transport, with each layer having tailored HOMO and LUMO energy levels to perform specific functions at that location
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 organic photodetector achieves improved external quantum efficiency and low dark current density, enabling effective photodetection with reduced energy barriers and enhanced charge separation, thus overcoming the limitations of silicon-based photodetectors.
Implementation Method 1
Photoelectric devices convert light and an electrical signal and include a photodiode and a phototransistor
Implementation Method 2
the first layer includes a p-type organic semiconductor and an n-type organic semiconductor... the n-type organic semiconductor may have a lowest unoccupied molecular orbital (LUMO) energy level lower than that of the p-type organic semiconductor
Data Source
AI summary
An organic photodetector includes: an anode; a cathode facing the anode; and an active layer disposed between the anode and the cathode and including a first layer and a second layer. The first layer is disposed between the anode and the second layer, the first layer includes a p-type organic semiconductor and an n-type organic semiconductor, and the second layer includes the p-type organic semiconductor.