Exact doping of semiconductor nanomaterials and X-ray characterizations

Semiconductor Quantum Dots (QDs) have great potential in applications for renewable energy generation due to their size-tunable redox potentials. QDs may also be doped to manipulate their electronic structure. Our group developed a method to dope each quantum dot with an exact number of guest ions by nucleating the QD around an organometallic seed cluster that contains guest ions. As a result, each QD has the same number of dopants, which eliminates problems due to inhomogeneity of the dot stoichiometry. These materials were studied using time-resolved X-ray absorption spectroscopy, which allows us to characterize the electronic and coordination structure in both the ground and excited states. It was found that, when dopants interact with charge carriers, they may alter their bonding to the underlying matrix. This phenomenon of charge carrier modulation of dopant bonding has a strong effect on the conductivity properties of doped semiconductors.