Photodoping and discharging dynamics in plasmonic semiconductor nanocrystals.

The pressing need to mitigate climate change and global warming underscores the critical importance of developing sustainable energy solutions. Transparent conducting oxide (TCO) zero-dimensional (0D) nanocrystals (NCs) such as indium-tin-Oxide (ITO) are of special importance for light driven opto-electrical devices because of their unique features of optical transparency in the visible region and controllable electrical conductivity. Doped metal oxide nanocrystals (MO NCs) are potential candidates for accumulating multiple electrons through the light-induced doping process termed ’Photodoping’. ITO NCs with different In2O3 (IO) shell thicknesses are charged using a UV LED in a controlled and inert atmosphere, simultaneously monitoring the changes in the absorption spectra over time with a time resolution of a few seconds. The role of hole scavengers in the photodoping process is investigated, with the aim of elucidating how their incorporation influences the photodoping mechanism and accelerates the rate of charge accumulation. In this way we extract information on the dynamics of the light-driven charging process of a set of ITO/In2O3 core/shell (ITO/IO) NCs with "artificial" depletion regions. To gain a deeper understanding of the mechanisms governing charge carrier generation and accumulation, photodoping experiments were performed on thin films composed of ITO nanoparticles. Our findings indicate two primary mechanisms occurring during photodoping: 1) depletion layer modulation within the nanoparticles, confirmed through the optical multilayer model and HEDA model, and 2) the surface sorption reactions of oxygen which accounts for the observed persistent photoconductivity upon cessation of UV illumination. These findings provide a comprehensive understanding of the fundamental processes underlying photodoping mechanisms of MO NCs in solution and solid-state systems. This knowledge paves the way for the rational design of ITO-based photocapacitors with enhanced performance and stability. By leveraging these insights, we can develop sustainable, light-driven devices that contribute to a greener future.