Researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL) have developed new designer quantum dot systems with greater control over beneficial properties for photoelectrochemical and photovoltaic solar applications.   The scientists were able to chemically modify lead sulfide (PbS) quantum dot surfaces so that their ionization energy – the amount of energy needed to remove a single electron from the solid – could be varied systematically from 6.5 eV to 4.1 eV (gr...