Quantum Dots and Their Applications - （量子点和他们的应用程序）.pdf

Quantum Dots: Science and Applications James McDaniel Physics 3500 Nanochemistry Why I chose this topic? • Useful Now: I chose to research and present on the science and applications of Quantum Dots because of the many interesting and important applications currently in use by this nano- technology. • The Future is Bright: The usefulness and application of Quantum Dot technology continues to expand and research is striving to bring their benefits to more and more technologically applied fields. What are Quantum Dots? • Quantum dots are semi- conductors that are on the nanometer scale. • Obey quantum mechanical principle of quantum confinement. • Exhibit energy band gap that determines required wavelength of radiation absorption and emission spectra. • Requisite absorption and Fig. 1. Schematic plot of the single particle resultant emission wavelengths energy band gap. The upper parabolic band dependent on dot size. is the conduction band, the lower the valence. Confinement - Infinite Square Well Potential Fig. 2. Quantized energy levels of a particle in a box. Quantum Dots Description… • The emission and absorption spectra corresponding to the energy band gap of the quantum dot is governed by quantum confinement principles in an infinite square well potential. • The energy band gap increases with a decrease in size of the quantum dot. Quantum Confinement Fig. 3. As the energy well, or the particle, shrinks the gap in energy levels increases. Fig. 4. The energy band gap associated with semi-conducting materials. In order to produce electric current electrons must exist in the con