Charge Carrier Extraction Following Multiple Exciton Generation (MEG) in Semiconductor Nanocrystals

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This project is designed to determine if the process of multiple excitation generation (MEG) can result in the extraction of excess charge carriers. The materials investigated will be nanocrystals of the lead chalcogenide salts, in particular lead sulphide. The nanoparticles will be attached to metallic gold and optically transparent electrodes using linking molecules. Subsequently the electrochemical and optoelectrochemical characterisation techniques of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Photoelectrochemical Spectroscopy (PECS) and Intensity Modulated Photocurrent Spectroscopy (IMPS) will be employed to investigate the PbS - electrode system. The data will be modelled and the charge carrier transfer processes and kinetics determined. This will be undertaken for codditions where MEG is absent, where it is present, for a range of different particle sizes and for low and high surface particle densities and then the data compared. Using the above techniques in combination with an electrochemical quartz microbalance (EQCM) study will allow the properties of the ensemble to be assigned on a per particle basis.