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Similar Prenucleation Clusters in Hot-Injection and Heating-Up Approaches to CdS Colloidal Semiconductor Quantum Dots
Wenlong Feng1, Kui Yu1, Yang Li1
1Engineering Research Center in Biomaterials, Sichuan University, Chengdu, Sichuan 610065, P. R. China.
The Journal of Physical Chemistry Letters
|April 24, 2026
Summary
Prenucleation clusters (PNCs) are crucial for synthesizing cadmium sulfide (CdS) quantum dots (QDs) using both hot-injection and heating-up methods. These PNCs transform into magic-size clusters (MSCs) at room temperature, supporting a two-step QD formation model.
Area of Science:
- Materials Science
- Nanotechnology
- Chemical Synthesis
Background:
- Colloidal semiconductor quantum dots (QDs) are vital nanomaterials with tunable optical and electronic properties.
- Hot-injection is a common method for QD synthesis, but understanding early-stage formation is key.
- The LaMer model is a widely accepted nucleation-growth theory for QD formation.
Purpose of the Study:
- To investigate the presence and role of prenucleation clusters (PNCs) in cadmium sulfide (CdS) QD synthesis.
- To compare QD formation via hot-injection and heating-up approaches.
- To evaluate the applicability of the LaMer and Yu models in explaining QD and magic-size cluster formation.
Main Methods:
- Synthesis of CdS QDs using cadmium oleate and sulfur precursors in 1-octadecene (ODE) and 1-tetradecanol (TDO) solvents.
- Characterization of reaction intermediates, including prenucleation clusters (PNCs).
- Temperature-dependent studies of PNCs and subsequent QD formation.
- Room temperature dispersion of PNC-containing samples to observe magic-size cluster (MSC) development.
Main Results:
- Similar prenucleation clusters (PNCs) were observed in both hot-injection and heating-up synthesis of CdS QDs.
- PNCs decomposed more rapidly at higher temperatures, leading to QD nucleation.
- Dispersing PNC-containing samples at room temperature resulted in the formation of magic-size clusters (MSCs), specifically MSC-311.
- The observed phenomena align better with the two-step model proposed by Yu than the LaMer model.
Conclusions:
- Prenucleation clusters (PNCs) are fundamental intermediates in CdS QD formation, regardless of the synthesis approach (hot-injection or heating-up).
- The temperature-dependent behavior of PNCs and the subsequent formation of MSCs are well-explained by a two-step nucleation and growth model.
- The findings challenge the direct applicability of the classical LaMer model for explaining these specific QD and MSC formation pathways.
