Quantum Dot Photodetector Buffer Layer for Low-Recombination IR Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current infrared photodetectors, particularly those using lead and mercury chalcogenides, face limitations due to toxicity, high cost, and restricted commercialization, while non-toxic alternatives like silver telluride quantum dots have shown poor performance in the past.
Innovation Solution
A photodetector device is developed using a light-active absorbing structure composed of silver chalcogenide quantum dots, specifically Ag2Te quantum dots, combined with a buffer structure of silver bismuth sulfide nanocrystals, which reduces interface recombination and enhances photo-detectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead chalcogenide or mercury chalcogenide quantum dots are used for infrared photodetection, then high photo-detectivity and external quantum efficiency are achieved, but toxicity limits applications and commercialization
Solution Approach 1:
The patent changes the material composition parameters by replacing toxic lead and mercury chalcogenides with non-toxic silver chalcogenide quantum dots, specifically adjusting the chemical composition to achieve similar optoelectronic properties without the harmful effects of heavy metals
Solution Approach 2:
The patent employs composite material structures by combining silver chalcogenide quantum dots with carefully engineered ligand systems and buffer layers, creating a composite architecture that maintains high photo-detectivity while eliminating toxicity through the use of environmentally friendly materials
2Object-affected harmful factors
If non-toxic silver telluride quantum dots are used as alternatives, then environmental friendliness is improved, but device performance with EQE and detectivity is poor
Solution Approach 1:
The patent introduces a buffer layer as an intermediary structure between the silver telluride quantum dots and the charge transport layers. This buffer layer mediates the interface interactions, reducing recombination losses and improving charge extraction, thereby enhancing the photo-detectivity of the otherwise environmentally friendly but underperforming silver telluride quantum dots
Solution Approach 2:
The patent optimizes multiple parameters including quantum dot size distribution, ligand composition and length, buffer layer thickness and material composition, and processing conditions to transform the poor-performance silver telluride quantum dots into high-performance photodetectors with EQE exceeding 50% and detectivity above 10^11 Jones
3Ease of manufacture
If colloidal quantum dots are used instead of epitaxial growth materials, then cost is reduced and solution-processibility is improved, but manufacturing precision and device performance consistency are challenging
Solution Approach 1:
The patent performs preliminary actions by extensively optimizing the colloidal quantum dot synthesis protocols, size distribution control, and surface ligand engineering before device fabrication. This pre-optimization ensures that the colloidal quantum dots possess narrow size distributions and consistent optoelectronic properties, enabling high-performance devices with solution processing while maintaining performance consistency
Solution Approach 2:
The patent systematically adjusts and optimizes multiple parameters including precursor ratios, reaction temperature and time, ligand types and concentrations, and annealing conditions to achieve precise control over quantum dot size, composition, and surface properties, thereby ensuring manufacturing precision and device performance consistency through solution processing
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 device achieves high responsivity, low noise, and high specific detectivity, with performance metrics such as responsivity up to 0.25 A/W, noise floor of 10 fA/Hz 0.5<, and specific detectivity up to 10 12< Jones, while being environmentally friendly and compatible with ROHS regulations.
Implementation Method 1
a light-active absorbing structure arranged over said electron transporting structure and containing a quantum dot population comprising silver chalcogenide quantum dots, made to absorb at least one of infrared light, near infrared light, and short-wavelength infrared light
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention relates to a photodetector device, comprising: - a substrate (S); - a first electrode (E1) defined by the substrate (S) or arranged thereon; - an electron transporting structure (ETL) arranged over the first electrode (E1); - a light-active absorbing structure (A) arranged over the electron transporting structure (ETL) and containing a quantum dot population comprising silver chalcogenide quantum dots, made to absorb at least one of infrared light, near infrared light, and short-wavelength infrared light; - a second electrode (E2) arranged over the light-active absorbing structure (A); and - a buffer structure (B), arranged between the electron transporting structure (ETL) and the light-active absorbing structure (A), wherein the buffer structure (B) is configured to reduce interface recombination.