Quantum Dot Semiconductor Device Ligand Engineering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photoelectric conversion elements suffer from current instability, particularly in the long-wavelength region, leading to noise and issues like image lag and photocurrent fluctuation.
Innovation Solution
A semiconductor device is designed with a specific layered structure, including an anode, a cathode, a first functional layer with a first quantum dot and a first ligand, and a second functional layer with a second quantum dot and a second ligand, where the second ligand is an aromatic compound with a sulfide bond and an ester bond, such as mercaptobenzoic acid (MBA).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric conversion elements use colloidal quantum dots with traditional ligands (1,3-benzenedithiol or 4-mercaptobenzoic acid), then photosensitivity in the long-wavelength region is improved, but current stability deteriorates causing noise and image lag
Solution Approach 1:
The photoelectric conversion layer is divided into multiple layers with different quantum dot sizes and ligand types. The first layer contains quantum dots with 1,3-benzenedithiol ligand for high photosensitivity, while the second layer contains quantum dots with aromatic sulfide-ester ligands for current stability. This segmentation allows each layer to perform its specialized function without interference.
Solution Approach 2:
Different regions of the photoelectric conversion layer are assigned different ligand types optimized for their specific functions. The first layer uses ligands optimized for light absorption and charge generation, while the second layer uses ligands optimized for charge transport and stability. This local optimization resolves the contradiction between photosensitivity and current stability.
2Device complexity
If a single-layer photoelectric conversion structure is used, then device complexity is reduced, but performance reliability deteriorates due to current instability
Solution Approach 1:
The photoelectric conversion layer is segmented into multiple functional layers, each with specific quantum dot and ligand combinations. This segmentation increases device complexity but resolves the reliability issue by separating the functions of light absorption and charge stability into distinct layers.
Solution Approach 2:
The patent uses composite material structures combining different quantum dot types and ligand systems in a layered architecture. This composite approach integrates the advantages of different material systems to achieve both high photosensitivity and current stability, resolving the reliability concern despite increased structural complexity.
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 semiconductor device achieves a stable current value when irradiated with light, reducing image lag and photocurrent fluctuation, thereby improving the performance and reliability of photoelectric conversion elements.
Implementation Method 1
photoelectric conversion elements having a photoelectric conversion layer containing an organic material or colloidal quantum dots have recently been developed
Data Source
AI summary
A semiconductor device includes an anode, a cathode, a first functional layer between the anode and cathode, and a second functional layer between the first functional layer and the cathode. The first functional layer contains a first quantum dot having a first ligand, and the second functional layer contains a second quantum dot having a second ligand different from the first ligand. The second ligand is an aromatic compound having a sulfide bond and an ester bond.