Study Of Surface Treatment Of Photoanode On The Performance Of Quantum Dot Sensitized Solar Cell

Quantum dot sensitized solar cell (QDSSC) is a kind of sensitized solar cell, but the currently low conversion efficiency limited its practically applicationbs. As its important role of photoanode serving as the support for the photosensitizer and the media for electron transfer, the properties of photoanode largely affect the performance of QDSSC. To improve the cell efficiency of QDSSC, we introduced in this thesis the surface treatments, studied the effect of surface treatment on the performance of QDSSCs. These include:1. we post-treated the PbS based quantum dot sensitized TiO2 film with I-/I2 solution, and studied its effect on the performance of QDSSC. The results showed that the post-treatment can significantly increase the photocurrent of the QDSSC, which results in a large enhancement of the solar-to-energy conversion efficiency from 3.21% for the as prepared cell to 4.32%. On variation of the solution constituent, we found that the photocurrent enhancement is close related to PbS QDs other than CdS. The benefit role of post-treatment is ascribed to the improved surface passivation of PbS QDs through a surface etching and simitaneous passivation caused by I-/I2 treatment, which promote the electron injection from QDs to TiO2. Time dependent photocurrent investigation indicates that the QDSSC upon post-treatment hold high stability.2. TiOl4 treatment on porous SnO2 film was carried out, and its effect on the performance of ZnS/CdS/PbS/CdS/SnO2/FTO QDSSC was investigated. Photovoltaic investigations showed that TiCl4 treatment largely increased the cell efficiency of the QDSSC. Also, it was found that the QDSSC with SnO2 film treated by TiCl4 followed by 100℃ drying achieved higher Voe (0.295 V), Jsc (12.5 mA cm-2) and overall solar-to-energy conversion efficiency (η=1.52%) as compared to that of with SnO2 film treated by TiCl4 followed by 450℃ sintering (Voc=265 mV,Jsc=10.9 mAcm-2,η=0.872%. UV absorption and impedance analyses indicate that the TiCl4 treatment leads to the increase of surface area of SnO2 film that enables more QDs to be deposted, whereas the electron injection from QDs to SnO2 is promoted. The higher efficiency of device made from SnO2 treated by TiCl4 followed by 100℃ drying compared to that of by 450 ℃ sintering is ascribed to its better lattice matching of SnO2 with TiO2 coating in the former case.