(color online) (a) Architecture and working mechanism of QDSC (FTO: fluorinated tin oxide; VB: valence band; CB: conduction band; Ox: oxidized species; Red: reduced species.^[28] (b) Main charge transfer processes occurred at TiO₂/QD/electrolyte interfaces including six major recombination paths: (i) recombination between photo-generated electrons in TiO₂ and sub-bands (or traps ) in QDs; (ii) recombination between photo-generated electrons in TiO₂ and holes in QDs; (iii) recombination between photo-generated electrons in QDs and oxidized species in the electrolyte; (iv) irradiative recombination between electrons and holes in QDs; (v) photo-generated electrons captured by traps; (vi) recombination between photo-generated electrons and oxidized species in the electrolyte.