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Observation and Analysis of Blinking Surface-enhanced Raman Scattering
Published on: January 11, 2018
Hole surface trapping in CdSe nanocrystals: dynamics, rate fluctuations, and implications for blinking
Francisco M Gómez-Campos1, Marco Califano
1Departamento de Electrónica y Tecnología de Computadores, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
Nano Letters
|August 2, 2012
Summary
Carrier trapping in nanocrystal devices degrades performance. Inorganic shells significantly reduce hole transfer rates, unlike core-only systems where trapping is very fast.
Area of Science:
- Materials Science
- Nanotechnology
- Quantum Dots
Background:
- Carrier trapping is a primary cause of performance loss in nanocrystal-based devices.
- The precise dynamics of carrier trapping remain poorly understood.
Purpose of the Study:
- To comprehensively investigate hole transfer efficiency to various trap sites in Cadmium Selenide (CdSe) nanocrystals.
- To analyze the impact of organic and inorganic passivation on carrier trapping dynamics.
- To provide guidelines for engineering trapping rates.
Main Methods:
- Utilized the atomistic semiempirical pseudopotential approach for theoretical calculations.
- Examined trap sites on the core, shell, and core/shell interface of CdSe nanocrystals.
- Differentiated the roles of coupling strength and energetics in trapping processes.
Main Results:
- Identified extremely efficient trapping in core-only systems, with rates significantly faster than radiative recombination.
- Demonstrated that inorganic shells can drastically reduce trapping rates, falling below typical radiative recombination rates.
- Separated the contributions of coupling strength and energetics to understand trapping behavior.
Conclusions:
- Developed general guidelines for optimizing trapping rates in nanocrystal devices.
- Highlighted the critical role of passivation strategies, particularly inorganic shells, in mitigating performance degradation due to carrier trapping.
- Provided insights into controlling charge carrier dynamics for improved nanocrystal device performance.
