| Since dyes sensitized solar cells (DSSCs) were invented in 1991, enormous attentions have been paid to improve its photoelectric conversion efficiency. In fact, for both traditional liquid dye-sensitized cells and perovskite solar cells (PSCs), the energy conversion properties of solar cells were mainly determined by the semiconductor materials of photo-anodes, which acted as the role of absorbing photosensitive, collecting and transmitting electrons. Specifically, the structure of the semiconductor materials affects the efficiency of the DSSCs and PSCs directly. Although T1O2 was one of the wildly used materials for photo-anode, but ZnO has advantages* of anisotropy, higher electronic transmission efficiency and similar band gap structure to T1O2 and has become promising candidate for photo-anode material.In this study, three kinds of ZnO based arrays with different morphologies were prepared by simple synthesis methods. The connections between grown conditions and structures or morphologes were investigated. The photovoltaic performances of these ZnO nanoarrays based DSSCs and PSCs were investigated and compared. The main contents include the following:1. One dimensional ZnO nanorods array which is beneficial to electric transfer was prepared on FTO substrate via hydrothermal method. The effect of duration of hydrothermal treatment on the nanorod growth was investigated. XRD, SEM and TEM methods were used to investigate the structures and morphologies of the ZnO film. The photovoltaic performances of ZnO nanorod array based DSSc and PSCs were investigated and compared. The results show that the DSSCs achieves the best efficiency (1.78%) when the film thickness is 3.04 um, while the PSCs achieves the best efficiency (2.36%) when the film thickness is 1.83 um. It can be concluded that the thickness plays an important role for solar cells. For DSSCs, the thicker ZnO film leads to higher efficiency because the thicker ZnO film has higher surface area for the adsorption of dyes. But for PSCs, the thicker ZnO film leads to worse efficiency because thinner ZnO film has the advantage of being full filled.2. A hierarchical porous F-ZnO nanoarray film was grown directly on FTO substrate. Precursory Zn(OH)F prisms array was synthesized by using a facile low temperature chemical bath process, after a subsequent annealing process, the porous ZnO prism array film was obtain. The morphology and the structure of the sample were characterized by SEM, TEM and HRTEM. The results show that the porous prism has a large inner surface and an approximate single crystalline structure. Porous prisms fabricated via different growth time were investigated in DSSCs and PSCs and highest conversion efficiency of 2.99% and 3.22% were obtained for DSSCs and PSCs, respectively.3. Hydrothermal and water-bath method was introduced to synthesis the ZnO prism array film and TiO2 nanoparticles (ZnO/TiO2 composite structure), respectively. The adherence of TiO2 nanoparticles improved the specific surface area of the ZnO arrays, comparing with the pure ZnO arrays, which has been proved by EIS test. We successfully assembled the DSSCs and the PSCs based on the ZnO/TiO2 composite structure. The DSSCs based on the ZnO/TiO2 composite structure has a PEC of 3.25%, which increase 82.5% comparing with the device based on the ZnO NR in the same lenghth. Meanwhile, the PSCs based on this structure also has a higher PEC of 4.2%, with a strong increase of 78.0%. At last, the stability of both DSSCs and PSCs were investigated. The efficiency of the DSSC declined 70% within only 24 h, while that of PSC even maintained 40% after 11 days. These results indicates that ZnO/TiO2 composite structure are more stable in PSCs than in DSSCs. |
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