Abstract
Two 4 mu m thick SnO2 photoelectrodes have been sensitized separately by N719 dye molecules and FeS2 quantum dots for a comparison study. PIA (photoinduced absorption spectroscopy), a multipurpose tool in the study of dye-sensitized solar cells, is also used to study quantum-dot based solar cells. PIA was employed to investigate the mechanistic properties of electrons under illumination conditions comparable to sunlight. PIA transient decays of both electrodes (in air) are attributed to hole-electron recombination or dye regeneration and does not follow simple first-order kinetic but is characterized by a range of recombination times. Incident-(Pseudo-) first-order rate constants for bleach at 420 nm and 550 nm are of approximately 0.15 ms and 19 us for N719 and FeS2 based solar cells, respectively. Photon-to-Current Efficiencies (IPCE) at 400 nm and 540 nm are 20 and 22%, respectively. Both short recombination rates constants and lower performances of both cells can be explained by the lower valence band of SnO2 electrodes and the presence of FeS2 phases other than the photoactive pyrite phase.