| TiO2 nanomaterial has been widely studied due to its unique properties such as photocatalytic activity, photovoltaic effect, dielectric permittivity, high chemical stability and low toxicity. At present, TiO2 has been applied in many areas, and the most striking one is sensitized solar cells, which may be an effective solution for energy crisis. The applications of TiO2 in dye-sensitized solar cells (DSSC) have been reported in 1991, and fast developed during the past 20 years. The present study found that the Nano TiO2 perovskite solar cell could used as a new type solar cell with great potential, which has been able to increase the conversion efficiency to more than 19%. And due to its substantially simple manufacturing process and excellent photoelectric performance, the study for TiO2 perovskite solar cells has become one of the forefront and hot topics.It was found that the morphologies and structures of TiO2 have great effects on its photoelectric properties. In comparison with nanoparticles and polycrystalline nanostructures, single-crystalline nanorod arrays have no grain boundary for electron scattering or trapping, as a result can offer a direct path for electron diffusion, which has attracted much attention.Therefore, this study mainly investigated the preparation of nano TiO2 and the characterizations of TiO2-based DSSC/perovskite solar cells. Main experiments and results are listed below:(1) TiO2 nanorods with multidirectional coral-like structure were synthesized through a facial hydrolysis and condensation method by using titanium oxysulfate (TiOSO4) as the precursor. After the deposition of amorphous TiO2 film on the FTO substrate, TiO2 nanorods continuously formed on the film in TiOSO4-H2O2 aqueous solution, The phase transformation to anatase and rutile TiO2 could be achieved through sintering treatment. TiO2 film formed on FTO substrates exhibited a double-layer structure, including the smooth film grown on the bottom and coral-like clusters dispersed evenly on the top. The base film of TiO2 on FTO is in anatase phase, while the nanowire clusters on top formed in rutile phase. In addition, dye sensitized solar cells (DSSCs) were fabricated with nanocoral structured TiO2 for the photoanode, and the highest photoelectrical conversion efficiency (η) of 0.9% was obtained from the DSSC that composed of 600 ℃ sintered TiO2.(2) We proposed a new type of all-solid-state dye-sensitized solar cells (DSSCs) containing two different perovskite materials for the first time, including SrTiO3 and CsSnI2.95Fo.05 as electron and hole transport medium, respectively. SrTiO3 nanocubes-TiO2 nanorods (STC-TRs) heterostructure nanocomposite was synthesized through a two-step hydrothermal method. It was demonstrated that N719/STC-TRs/ CsSnI2.95F0.05 system with well-matched energy band could function as an energetical junction to accelerate charge separation, and thus to improve photoconversion efficiency of DSSCs. In particular, the influence of alkaline precursor reactant concentration on photoelectrochemical properties of STC-TRs films was discussed, and it was proved that with optimized SrTiO3 loading, STC-TRs photoanode could increase the power conversion efficiency (η) of DSSCs to 1.09%, i.e.10 times higher than that of cells with pure TiO2 nanorod array prepared under alkaline circumstance (η-0.12%). As a result, heterostructured STC-TRs nanocomposite provided both enhanced photoconversion efficiency and a desirable potential for large-scale industrial production of TiO2 usually done under alkaline condition.(3) In this study, heterostructured TiO2-SrTiO3 nanorod array films were synthesized through a two-step hydrothermal method. The perovskite SrTiO3 cubic nanoparticles were evenly deposited on the surface of single-crystallized TiO2 nanorod arrays. All-solid-state solar cells were fabricated with TiO2-SrTiO3 heterostructured composite as the photoanode, the perovskite CH3NH3PbI3 and CsSnI2.95F0.05 as the sensitizer and electrolyte respectively. From photoelectrical measurement, the performance of solar cells was highly improved by varying the sintering temperature and the concentration of strontium precusor. The highest photoelectrical conversion efficiency of SrTiO3-TiO2 system reached 0.34%, which was about 2 times of the undecorated TiO2 system. |
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