Near-Infrared Light Detector With Wavelength-Selective Active Layer
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Solution Overview
Problem
Conventional light detecting elements face challenges in achieving high sensitivity in specific detection wavelength regions due to complex structures and inefficiencies, particularly in near infrared wavelengths, despite the use of optical filters.
Innovation Solution
A light detecting element with a configuration including a p-type semiconductor material and an n-type semiconductor material in the active layer, where the thickness is at least 800 nm, the p/n ratio is at most 99/1, and the work function of the surface in contact with the active layer on the negative electrode side is lower than the LUMO energy level of the n-type semiconductor material, resulting in a narrow peak external quantum efficiency in the near infrared wavelength region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical filter is used to increase sensitivity in a predetermined detection wavelength region, then sensitivity in the detection wavelength region is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the optical filtering function with the active layer by incorporating specific p-type and n-type semiconductor materials directly into the photoelectric conversion element. This integration eliminates the need for separate optical filters while achieving wavelength-selective detection, thereby improving sensitivity in predetermined wavelength regions without increasing device complexity
Solution Approach 2:
The patent changes the material parameters of the active layer by using specific p-type semiconductor materials (with HOMO energy levels of 5.5-6.5 eV) and n-type semiconductor materials (with LUMO energy levels of 3.5-4.5 eV). This parameter optimization enables the active layer itself to function as a wavelength-selective filter, resolving the contradiction between sensitivity improvement and structural simplification
2Measurement precision
If an optical filter is used to block light outside the detection wavelength region, then sensitivity in the detection wavelength region is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the wavelength-selective detection function with the photoelectric conversion function in a single integrated structure. By incorporating semiconductor materials with specific energy levels into the active layer, the element achieves both functions simultaneously, eliminating the need for separate optical filters and simplifying the manufacturing process
Solution Approach 2:
The patent uses composite semiconductor materials with specifically selected energy level characteristics (p-type with HOMO 5.5-6.5 eV and n-type with LUMO 3.5-4.5 eV) to create an active layer that inherently provides wavelength selectivity. This composite material approach achieves the filtering effect through material properties rather than additional structural components, thereby easing manufacturing
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 enables high sensitivity in predetermined wavelength regions, specifically near infrared wavelengths, with a simpler structure without the need for additional optical components, while maintaining low sensitivity in other regions.
Implementation Method 1
The energy (hυ) of light incident on the active layer generates electric charges (holes and electrons) in the active layer
Implementation Method 2
the generated holes move toward the positive electrode
Implementation Method 3
the electrons move toward the negative electrode
Data Source
AI summary
This light detecting element has a simple configuration, and is highly sensitive to a prescribed wavelength region. The light detecting element comprises a positive electrode, a negative electrode, and an active layer that is provided between the positive electrode and the negative electrode, and that includes a p-type semiconductor material and n-type semiconductor material. The thickness of the active layer is at least 800 nm. The weight ratio between the p-type semiconductor material and the n-type semiconductor material included in the active layer (p/n ratio) is at most 99/1. The work function of the negative electrode side surface in contact with the active layer is lower than the absolute value of the LUMO energy level of the n-type semiconductor material.