CdS core-type quantum dots, 5 mg/mL in toluene

CdS core-type quantum dots

Introduction

CdS (Cadmium Sulfide) core-type quantum dots are semiconductor nanocrystals made of cadmium sulfide, a II-VI group material. These quantum dots are considered core-type because they consist of a cadmium sulfide core without any shell layer surrounding them. Like other semiconductor quantum dots, CdS quantum dots exhibit quantum confinement effects, where their electronic and optical properties are significantly influenced by their size. This makes them highly tunable and versatile for various applications.

CdS quantum dots are known for their bright fluorescence, high photoluminescence quantum yield, and tunable emission, depending on the size of the quantum dot. They typically emit in the visible spectrum (blue to green) and are widely used in fields such as optics, electronics, bioimaging, and sensors.

However, while CdS quantum dots exhibit excellent optical properties, cadmium is toxic, which raises concerns about their environmental impact and biological safety. To mitigate these concerns, core-shell quantum dots (where CdS cores are coated with materials like ZnS or ZnSe) are often developed to improve their stability and reduce their toxicity.

Properties

Size-Tunable Optical Properties:

Tunable Emission: The emission wavelength of CdS quantum dots can be adjusted by controlling their size. Smaller CdS quantum dots typically emit light at shorter wavelengths (blue or green), while larger dots emit light at longer wavelengths.

Wide Absorption Spectrum: CdS quantum dots absorb light across a broad spectrum, including the ultraviolet (UV) and visible regions, with a high absorption efficiency, making them suitable for many optical applications.

High Photoluminescence Efficiency:

CdS quantum dots are known for their high quantum yield, meaning they emit a large amount of light when excited by a source. This makes them useful for applications requiring high brightness, such as fluorescence microscopy or LEDs.

Bright Fluorescence:

CdS quantum dots have strong fluorescence properties, making them suitable for imaging and sensing applications. Their fluorescence is stable over time, allowing for long-term monitoring in some contexts.