Composition-dependent trap distributions in CdSe and InP quantum dots probed using photoluminescence blinking...

Area of Science:

• Materials Science
• Nanotechnology
• Quantum Dot Research

Background:

• Group II-VI quantum dots (QDs) offer broad applications but contain toxic ions, raising environmental concerns.
• III-V QDs are developed as a nontoxic alternative, but their optical properties require further comparative analysis.

Purpose of the Study:

• To explore composition-related energetic trap distributions in different core/multishell quantum dot structures.
• To compare the optical properties and charge trapping dynamics of II-VI and III-V quantum dots.

Main Methods:

• Investigated three core/multishell QD types: CdSe-CdS (CdSe/CdS/ZnS), InP-ZnSe (InP/ZnSe/ZnS), and InP-GaP (InP/GaP/ZnS).
• Analyzed photoluminescence blinking dynamics to determine probability density plots and Auger ionization efficiencies.
• Quantified trap densities at higher energy states relative to the band gap energy (Eg).

Main Results:

• CdSe-CdS (II-VI) QDs exhibited significantly higher trap densities compared to InP-based (III-V) QDs at energy states above the band gap.
• Trap density was found to be closely associated with the composition of the encapsulated QDs.
• Photoluminescence blinking dynamics provided insights into charge trapping processes.

Conclusions:

• The composition of quantum dots critically influences charge trapping mechanisms.
• InP-based (III-V) QDs present a promising, environmentally friendly alternative to II-VI QDs due to lower trap densities.
• Findings guide the development of safer and more efficient QD-based devices.