Electron Transfer Theory in Single Molecule Studies of Intermittent Fluorescence of Quantum Dots and in Initial Steps in Dye Sensitized Solar Cells
Presenter: Rudolph Marcus
Published: July 2015
Age: 18-22 and upwards
Views: 741 views
Intermittently fluorescing single molecule systems are found in many materials, including semiconductor quantum dots (QD), dyes on crystalline or nanoparticle film surfaces, and biological systems. The QD’s show a ~ -3/2 power law for the distribution of ‘on’ and ‘off’ times. For the ‘on’ states there is also an exponential tail whose importance increases with increasing light intensity. We interpret these and additional QD results in terms of a diffusion/electron transfer (ET) theory (spectral diffusion). Less studied than QD’s is the single molecule dye-photoinjection of electrons or holes into semiconductors or into their films of nanoparticles, of solar cell interest. Here, an injection can be either into a conduction band (valence band in the case of hole injection) or into the band gap, followed by diffusion of the carrier. We describe a diffusion/ET theory, leading to different kinetics for band and band gap injection and recombination and to the observed ~ -1 power law.