Cadmium-Selenide (CdSe) Quantum Dots - Emission and Size Properties
Cadmium-Selenide (CdSe) Quantum Dots - Emission and Size Properties
This Demonstration visualizes the relationship between the diameter of Cadmium-Selenide (CdSe) quantum dots and their emission properties, including the resulting emission wavelength and energy in electron volts. Adjust the "diameter (nm)" slider to see how changes in particle size affect the quantum dot's optical characteristics.
Details
Details
This demonstration uses mathematical models to calculate the energy and corresponding emission wavelength of CdSe quantum dots based on their diameter. The quantum dot's diameter influences the energy levels due to quantum confinement effects, where smaller sizes lead to higher energy gaps.
To accurately model the relationship between diameter and energy levels, a linear bijection transformation is applied to the diameter in the energy calculation formula. This transformation adjusts the diameter values to fit within the effective size range observed in experimental studies of CdSe quantum dots. The transformation is defined as follows:
Adjusted Diameter:
((Diameter + 6.88)/9.2)*10-9
The energy of the quantum dots is then calculated using the following formula:
E=h^2/(8m(Adjusted Diameter))
To accurately model the relationship between diameter and energy levels, a linear bijection transformation is applied to the diameter in the energy calculation formula. This transformation adjusts the diameter values to fit within the effective size range observed in experimental studies of CdSe quantum dots. The transformation is defined as follows:
Adjusted Diameter:
((Diameter + 6.88)/9.2)*10-9
The energy of the quantum dots is then calculated using the following formula:
E=h^2/(8m(Adjusted Diameter))
Where:
'h' is Planck's constant (6.62607015 × 10^-34 Joule-second),
'm' is the effective mass of an electron in CdSe (0.13 times the mass of an electron, 9.10938356 × 10^-31 kg),
'Diameter' is the original diameter of the quantum dot in nanometers before adjustment.
The emission wavelength, 𝜆, corresponding to this energy is given by the equation:
1240/(E/eV)
Where:
eV is the energy equivalent of one electronvolt (1.60218 × 10^-19 Joules).
'h' is Planck's constant (6.62607015 × 10^-34 Joule-second),
'm' is the effective mass of an electron in CdSe (0.13 times the mass of an electron, 9.10938356 × 10^-31 kg),
'Diameter' is the original diameter of the quantum dot in nanometers before adjustment.
The emission wavelength, 𝜆, corresponding to this energy is given by the equation:
1240/(E/eV)
Where:
eV is the energy equivalent of one electronvolt (1.60218 × 10^-19 Joules).
References
References
References for demonstration.
Permanent Citation
Permanent Citation
Valeria Mas and Josie Hodges
"Cadmium-Selenide (CdSe) Quantum Dots - Emission and Size Properties"
http://demonstrations.wolfram.com/CadmiumSelenideCdSeQuantumDotsEmissionAndSizeProperties/
Wolfram Demonstrations Project
Published: March 30, 2025