Nanoparticles is typically used for particles in the nm size regime, while quantum dots are those nanoparticles that are in "quantum size regime" characterized by the discretization of the energy levels inside the material. For semiconductor nanoparticles, the quantum size regime is obtained when their dimensions are smaller than the exciton Bohr radius (for example in CdS such a threshold value is about 5.4nm). For metal nanoparticles, is not so easy to define the conditions for the quantum size regime. You have to calculate the density of the electronic states as a function of the volume of the nanoparticles. You can refer to this articles: Quantum size effects in metal particles, Rev. Mod. Phys. 58, 533 (1986). I can tell you that for example for Au nanoparticles the threshold for quantum size regime is about 2 nm diameter.

I think quantum dots are mainly refered to semiconductor nanoparticles.

Nano-particles term used as broad term in for material (e.g. gold nanoparticles, silver nanoparticles, CdSe QDs, nZVI, nano-chemosensors, nano biosensors and others which are nano in ranges) which are in nano range, whether QDs are specific materials which are synthesized or developed with certain elements like Cadmium, Selenium, Zinc Oxide (CdSe, CdTe, CdS and others).

So, Quantum dots are subjected in the term of nanoparticles because of its sized is in nano scale.

Nanoparticles is typically used for particles in the nm size regime, while quantum dots are those nanoparticles that are in "quantum size regime" characterized by the discretization of the energy levels inside the material. For semiconductor nanoparticles, the quantum size regime is obtained when their dimensions are smaller than the exciton Bohr radius (for example in CdS such a threshold value is about 5.4nm). For metal nanoparticles, is not so easy to define the conditions for the quantum size regime. You have to calculate the density of the electronic states as a function of the volume of the nanoparticles. You can refer to this articles: Quantum size effects in metal particles, Rev. Mod. Phys. 58, 533 (1986). I can tell you that for example for Au nanoparticles the threshold for quantum size regime is about 2 nm diameter.

in many materials which are made Nano they are not passivated and they tend to aggregate. these QDs are surface passivated so that the aggregation is avoided. they do come in quantum size regime which mainly function due to quantum confinement effect. and due size tunable optical property they are made very special unlike any other materials, also sometimes they are considered as artificial atom.

This is partially historical as the concept of "quantum confinement" predates the recent emergence of "nanoparticles", but Vincenzo Rasta is correct in that the concept of "quantum confinement" (2D wells, 1D wires, 0D dots) was used to describe the phenomena observed when dimensions of solids (largely semiconductors were reduced to the size regime where quantum effects began to dominate (eg quantum Hall effect). nanoparticles are defined according to size alone

Nanoparticles ranging from 1nm to 100 nm including metal, polymer, semiconductor etc

quantum dot ranging from 0.1nm to 10nm with semiconducting materials.

All opinions are right, I consider that nanoparticles are crystals (metallic, semiconductor, etc) with a wide size distribution. If you have a size control on semiconductor nanoparticles, then you've earned quantum dots.

Thanks to all of you.

BALAMURUGAN Matheswara can you give me the refrence of that quantum dot less than 1nm?

I think the main difference between the nanoparticle and quantum dots is that the nanoparticle to be of the same material (ie, nanoparticle material substrate material is the same). As for quantum dots they are composed of a material different from the substrate material, so it consists confinement or quantization of energy.

Vincenzo Resta commented an important parameter, the Exciton Bohr Radius (EBR). Each semiconductor material has a characteristic value and serves as a criterion to define the quantum dot. Lead chalcogenides (PbS, PbTe, PbSe), as example, have a large EBR (42 nm for PbSe), then, 3-5 nm nanocrystals exhibit a strong quantum confinement.

Nanoparticles are such materials whose dimensions are in the range of nanometer,But quantum dots are such nanoparticle whose size comparable to exciton bhor radius. generally exciton bhor radius is different for different mateials.The exciton bhor radius depend on the effective mass of electron and hole and dilectric constant, which is different for different materials. When the size of QD below the exciton bhor radius , this is refered as strong confinement and if the size is greater than exciton bhor radius it is said weak confinement effect.

What is the size of polymeric Quantom Dots ? and Application

Quantum dots is a term referred to semiconductor particles. Nanocrystal can be defined as any inorganic entity in which there is a crystalline arrangement of constituent atoms or ions.

A nanoparticle can be of any material of nanodimensions in all directions. A quantum dot is one in which the electronic wavefunctions of the bulk material are confined by the spatial dimensions of the particle.

Dear huan Wang,

Can you please give that quantum dot reference given by balamurugan matheswara

Thanks for your answer. Would you tell me when we should or better to use quantum dot.

Nice explanations..