Quantum Dot Semiconductor Film Inter-Dot Distance Reduction
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Solution Overview
Problem
Semiconductor films with colloidal quantum dots exhibit insufficient inter-dot proximity due to large ligands, resulting in unfavorable photoelectric conversion characteristics and high risk of film detachment, limiting photocurrent values to several hundred nanoamperes.
Innovation Solution
A semiconductor film with quantum dots having an average shortest inter-dot distance of less than 0.45 nm, achieved by using specific amine-based ligands or thiocyan-based ligands to coordinate with the quantum dots, reducing inter-dot distance and enhancing electrical conductivity while preventing film detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large ligands are used to coordinate with quantum dots, then quantum dots can be stabilized, but inter-dot distance increases and electrical conductivity decreases
Solution Approach 1:
The patent applies parameter changes by transitioning from large ligands to small molecule ligands (such as thiocyanate ions, halide ions, or their combinations), fundamentally changing the ligand size parameter. This enables the inter-dot distance to be reduced from typically several nanometers to less than 0.5 nm, while maintaining quantum dot stability through the chemical coordination capability of the small molecule ligands.
2Manufacturing precision
If short ligands are used to reduce inter-dot distance, then electrical conductivity improves, but film detachment occurs
Solution Approach 1:
The patent employs composite materials by using mixed ligand systems combining small molecule ligands (for reducing inter-dot distance and improving conductivity) with stabilizing agents or specific molecular structures that provide film adhesion. This composite approach allows simultaneous achievement of short inter-dot distances and film stability, overcoming the limitation of using only short ligands.
3Productivity
If quantum dots are brought closer together to improve conductivity, then photocurrent increases, but film detachment risk increases
Solution Approach 1:
The patent changes the ligand parameter from large organic ligands to small molecule ligands with specific chemical properties (such as thiocyanate, halide ions), enabling inter-dot distances to be reduced to less than 0.5 nm. This parameter change simultaneously achieves high photocurrent values (exceeding 100 μA/cm²) and film stability by maintaining strong quantum dot-substrate interaction.
4Ease of manufacture
If conventional ligands are used, then quantum dots can be synthesized, but photocurrent values are limited to several hundred nanoamperes
Solution Approach 1:
The patent fundamentally changes the ligand parameter from conventional large ligands (such as oleic acid, oleylamine) to small molecule ligands (thiocyanate ions, halide ions, or their combinations). This parameter change enables photocurrent values to increase from several hundred nanoamperes to exceeding 100 μA/cm², while quantum dots can still be effectively synthesized and stabilized through the coordination chemistry of the small molecule ligands.
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 approach results in a semiconductor film with high photocurrent values and suppressed film detachment, enabling efficient photoelectric conversion and improved electrical conductivity.
Implementation Method 1
a semiconductor film which includes a cluster of semiconductor quantum dots each having a metal atom and ligands coordinating to respective semiconductor quantum dots
Implementation Method 2
solar cells in which colloidal quantum dots are used are reported to be able to increase the quantum efficiency due to, for example, the multiexciton generation effect
Implementation Method 3
solar cells in which colloidal quantum dots are used are reported to be able to increase the quantum efficiency due to, for example, the multiexciton generation effect
Data Source
AI summary
A semiconductor film includes a cluster of semiconductor quantum dots each having a metal atom and ligands coordinating to respective semiconductor quantum dots, and the semiconductor quantum dots have an average shortest inter-dot distance of less than 0.45 nm. A solar cell, a light-emitting diode, a thin film transistor, and an electronic device include the semiconductor film.