New Photovoltaic Devices Based on the Sensitization of p-type Semiconductors: Challenges and Opportunities

摘要

Because solar energy is the most abundant renewable energynresource, the clear connection between human activity and globalnwarming has strengthened the interest in photovoltaic science. Dye-nsensitized solar cells (DSSCs) provide a promising low-cost technologynfor harnessing this energy source. Until recently, much of the researchnsurrounding DSSCs had been focused on the sensitization of n-type semi-nconductors, such as titanium dioxide (Gra ¨ tzel cells). In an n-type dye-nsensitized solar cell (n-DSSC), an electron is injected into the conductionnband of an n-type semiconductor (n-SC) from the excited state of the sen-nsitizer. Comparatively few studies have examined the sensitization ofnwide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), thenphotoexcited sensitizer is reductively quenched by hole injection into thenvalence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control thenrate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as effi-nciently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO2-photosensi-ntized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-ncost photovoltaic devices whose photoconversion efficiencies could exceed 15%.