Effects of interface-potential smoothness and wavefunction delocalization on Auger recombination in colloidal
Xiaoqi Hou1, Yang Li1, Haiyan Qin1
1Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, People's Republic of China.
The Journal of Chemical Physics
|December 23, 2019
Summary
Controlling wavefunction delocalization, not interface smoothness, is key for engineering Auger recombination in colloidal quantum dots (QDs). Decreased hole delocalization significantly increases Auger rates, guiding QD design for optical applications.
Area of Science:
- Materials Science
- Quantum Mechanics
- Nanotechnology
Background:
- Auger nonradiative recombination is a critical factor limiting the efficiency of colloidal quantum dots (QDs) in optical and optoelectronic devices.
- Effective engineering of Auger processes in core/shell QDs is essential for improving device performance.
- Two proposed strategies for Auger engineering include controlling interface-potential smoothness and wavefunction delocalization.
Purpose of the Study:
- To investigate the influence of interface-potential smoothness and wavefunction delocalization on Auger nonradiative recombination rates in high-quality CdSe-based core/shell QDs.
- To determine the relative importance of these two strategies for Auger engineering.
- To provide guidelines for the rational design of QDs with tailored optoelectronic properties.
Main Methods:
- Fabrication of a series of CdSe-based core/shell QDs with high optical quality single-exciton states.
- Experimental measurement of biexciton quantum yields and Auger nonradiative recombination rates.
- Systematic variation of core/shell interface properties and wavefunction delocalization.
Main Results:
- Interface-potential smoothness showed minimal impact on biexciton quantum yield and Auger rates when using identical CdS outer shells.
- Decreased hole wavefunction delocalization led to a substantial increase (∼400%) in positive trion Auger rates.
- Mildly decreased electron wavefunction delocalization resulted in a moderate increase (∼50%) in negative trion Auger rates.
- Observed effects of interface smoothing on Auger rates were attributed to alterations in wavefunction delocalization.
Conclusions:
- Wavefunction delocalization is a more critical parameter than interface-potential smoothness for controlling Auger recombination in these core/shell QDs.
- Rational design of QDs should prioritize control over wavefunction delocalization to enhance performance in optical and optoelectronic applications.
- Findings offer practical guidance for developing next-generation quantum dot technologies.
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