Ultrafast electron transfer between molecule adsorbate and antimony doped tin oxide (ATO) nanoparticles

Ultrafast transient IR spectroscopy has been used to examine the effect of doping on interfacial electron transfer (ET) dynamics in Re(dpbpy)(CO)(3)Cl (dpbpy = 4,4'-(CH2PO(OH)(2))2-2,2'-bipyridine) (ReC1PO(3)) sensitized ATO (Sb:SnO2) nanocrystalline thin films. In films consisting of particles with 0%, 2% and 10% Sb dopant, the rates of electron injection from the adsorbate excited state to ATO were independent of and the rates of the recombination increased with the doping level. The observed similar forward electron injection rates were attributed to negligible changes of available accepting states in the conduction band at the doping levels studied. The dependence of the recombination rate on conduction band electron density and a possible mechanism for the recombination process were discussed.