LAUSR

Nitroxide radical redox-couple compounds have the potentials to be applied as a redox couple in dye-sensitized solar cell applications since their standard reduction potential reached almost 1 V. Unfortunately, many reports revealed the limitations of nitroxide in dye-sensitized solar cell applications. This study investigates the interaction between several nitroxide radical redox couples with anatase surface. The Ti14O31H6 cluster was built as a model of anatase surface. The calculation results show that the limitation of the nitroxide radical redox-couple compounds was laid on the high charge transfer on the TiO2 surface. The high charge transfer indicates that the charge recombination from the redox-couple species to the semiconductor is preferable and is not beneficial for cell efficiency. The calculation also figures that almost the observed nitroxide radical compounds shifted the TiO2 conduction band positively to the − 2.5 eV. This finding proved to us that it is important to choose the sensitizer which has a LUMO above − 2.5 eV to avoid the fail of charge injection.