Design Novel Photoanode And Optimize Properties Of Semiconductor Sensitized Solar Cells

Semiconductor sensitized solar cells possess many adavatagnes, for example,simple process and low cost. Especially, when the size of semiconductor sensitizers isless than its Bohr radius, they may exhibit some useful effects such as quantumconfinement, mini-band, and multiple exciton generation, which are benifical for thephoto-electron conversion. In this thesis, we focused on the designation andfabrication of novel photoandoes for semiconductor sensitized solar cells. The mainresearch results are as follows:First, we fabricated three dimensional networks of indium tin oxide (ITO)nanofibers on conductive glass substrate by using an electrospinning process.Light-harvesting CdS nanocrystals were electrodeposited onto ITO nanofibers, andthen obtained ITO/CdS coaxial nanofibers were constructed into SSSC. We found theperformance of this novel SSSC is remarkably superior to that with CdS nanocrystalsdirectly deposited on flat conductive substrate, and an unprecedented photocurrentdensity of9.27mA/cm~2is achieved.Secondly, we demonstrated the fabrication of n-type CdS and p-type CdTeco-sensitized ZnO nanowire arrays on conductive glass substrate by electrochemicaldeposition methodology. Substantial photocurrent and efficiency enhancement wasobserved in ZnO/CdS/CdTe electrode compared with ZnO/CdS and ZnO/CdTeelectrodes. Dynamic analysis of carrier transportation confirmed that the stepwiseband structure of ZnO/CdS/CdTe could facilitate the propagation and kineticseparation of photogenerated charges, and significantly reduced the electron transportresistance and achieved a long electron diffusion length and an overall highconversion efficiency.Thirdly, we constructed three dimentional conductive CdS networks for solarapplication. It was found that the photoelectric conversion efficiency could beimproved by slow annealing. EIS analysis showed that the slow annealing improvedthe electron transfer and prolonged the electron lifetime, thus enhanced thephotocurrent and then final performance significantly.