Lecture 23 - Semiconductor Nanotechnology Semiconductor...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chem 172 Advanced Inorganic Chemistry Lecture 25/June 2 nd Semiconductor Nanotechnology & Solar Cells Semiconductor Nanotechnology Semiconductor Nanocrystals: Quantum Dots ¾ Semiconductor nanocrystals of a few nanometer diameter can exhibit size dependent optical properties due to quantum confinement. ¾ This unique characteristic can enable new opportunities for energy harvesting in solar cells, color luminescent material for display, and image tags for biomedicine. E QD = E g + C/R 2 E QD = hv = hc/ λ = 1240/ λ How small is “Nano”? Single Hair = 100 micrometers = 100,000 nanometers ! 1 nanometer = one billionth (10 -9 ) meter Width = 0.1 mm Smaller Still DNA 3 nanometers Hair 100,000 nanometers 6,000 nanometers Red blood cell NANO is Not Simply A Miniaturization Play Not just smaller . . . . . . different because it’s smaller Size-Dependent Properties At the nanometer scale, properties become size-dependent. ¾ Chemical properties – reactivity, catalysis ¾ Thermal properties – melting temperature ¾ Mechanical properties – adhesion, capillary forces ¾ Optical properties – absorption and scattering of light ¾ Electrical properties – tunneling current ¾ Magnetic properties – superparamagnetic effect Nanomaterials can often display characteristics that are fundamentally different than those of their “bulk” counterparts.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Approaches to Nanoscale Structures ± Through the control of material growth atom by atom, bottom up approach provides a powerful route to nanostructures as small as a few nanometers. ± Chemists play a major role in nanoscience and nanotechnology. Top-down Lithography Mechanical grind Bottom-up Chemical synthesis Biological assembly Bulk Nano Atom CdSe Nanocrystals ¾ Organic molecules ‘cap’ the outer surface of core semiconductor. They prevent aggregation, oxidation, and stabilize nanoparticles in the solution.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Lecture 23 - Semiconductor Nanotechnology Semiconductor...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online