NORTHERN UNIVERSITY
BAN G LAD E S H
Knowledge for Innovation & Change
QUANTUM DOTS
PRESENTED BY SHIAM AHAMED LUVON
ID: EEE29200100576
DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING
INTRODUCTION
Quantum dots are tiny particles or nanocrystals of a semiconducting material with diameters in the range of 2-10 nanometers
(10-50 atoms). Quantum dots are nanoscale semiconductor particles that exhibit unique optical and electronic properties due
to their small size and quantum confinement effects. They are typically made of materials such as cadmium selenide, cadmium
sulfide, or indium arsenide, and can be synthesized in a variety of shapes and sizes, ranging from a few nanometers to a few
micrometers in diameter.
When excited by light or electrical current, quantum dots can emit bright, tunable light across a wide range of colors, making
them useful in a variety of applications such as displays, lighting, and biomedical imaging. Quantum dots are also being
studied for use in quantum computing, as they can serve as qubits, the basic units of information in quantum computers.
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HISTORICAL BACKGROUND OF
QUANTUM DOTS
Quantum Dots were first discovered in a glass matrix in 1981 by the Russian scientist Alexey Ekimov
whilst working at the Vavilov State Optical Institute in St. Petersburg. However, the first colloidal solutions
of Quantum dots were discovered by Louis Brus who was working on semiconductors at the AT&T Bell
Laboratories in New Jersey. He is now the Professor of Chemistry at Columbia University. In two papers
published in 1983 and 1984, Brus described Quantum dots as "small semiconductor crystallites".
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FABRICATION OF QUANTUM DOTS
There are several ways to fabricate quantum dots. Possible methods include
Basic methods:
Colloidal chemistry, (Cadmium selenide CdSe)
Electrostatic,
Lithography.
Epitaxy:
Fluctuation,
Self-organized,
Patterned growth.
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PROPERTY OF QUANTUM DOTS
 The most characteristic property is that their colour is size dependent and thus can be controlled
during synthesis.
 This arises as a result of quantum confinement effect.
 Smaller dots emit higher energy light, that is bluer in colour
whereas larger dots emit lower energy red light.
 QDs can emit light at wavelengths ranging from the ultraviolet
(UV) to the infrared (IR).
 The bandgap of QDs exhibits a never observed before direct
relationship to their size.
 The energy band gap is inversely proportional to the size of
quantum dots. We can vary the energy band gap by changing the size of the quantum dots. This
property of quantum dots makes it possible to use them in a variety of applications.
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APPLICATIONS OF QUANTUM DOTS
Some of the applications of quantum dots include:
 Solar Cells
 Photocatalysts
 Lasers
 OLED or QLED
 Computing
 Biology etc.
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FUTURE ASPECT OF QUANTUM DOTS
 Future QD displays will provide high-quality pictures for both TVs and monitors using QD materials.
 QDs may be used in defense applications or counter espionage such as protection against friendly fire
events by integrating quantum dots into dust that tracks enemies.
 Cancer was the ghost of death in the world until now, QDs may be used to treatment besides detection for
cancer diseases, such as leukemia, ovarian cancer, prostate cancer, breast cancer, and pancreatic cancer.
 Future research expects to seek less toxic QDs such as GQDs having unique optical properties, and it
involves many applications such as different types of bioapplications (biosensing and bioimaging), solar
cells, LEDs, and photocatalysis.
 In the future, it expects the integration of materials or techniques, such as magnetic and electric material
or signal application techniques, that lead to powerful biosensing QDs. Now, researchers will continue the
synthesis of QDs in a green approach that demands better stability, biocompatibility, and unique optical
properties.
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THANK YOU..