| One-dimensional TiO2 nano-materials has been recognized as one of the most promising inorganic semiconductor nanostructures. It have attracted much attention in solar energy and application field, for the good chemical stability, unique geometrical and the excellent photoelectrical and electrical properties of TiO2 nanostructures. In this dissertation, we present a novel, high-yield, special morphology and size-controllable TiO2 nanorods.We carried out our research on the controllable synthesis and growth mechanism of oriented attachment TiO2 nanorods. And discuss the application of the as-prepared TiO2 nanorods in dye/quantum dot-sensiitzed solar cell (DSSC/QDSSC) and mesoporous perovskite solar cell (MPSC). The main results are listed below:In this work, by using titanium isopropoxide (TTIP) as Ti source, ethylene glycol (EG) as inhibitors reagent and tetramethylammonium hydroxide (TMAOH) as sol reagent, hydrothermal method for the preparation of singlecrystal-like anatase TiO2 nanorods (NRs) with specific (101) exposed crystal planes and preferred [001] growth direction, which is governed by the "oriented attachment" mechanism. The successful synthesis of TiO2 NRs and fine tuning on their size and shape could be easily accomplished by adjusting the solvent compositions. The NRs'morphology could be finely tuned by the concentrations of titanium isopropoxide, and tetramethylammonium hydroxide, and their relative molar ratios.Three kinds of oriented attachment TiO2 NRs (short-thin, long-thin and long-thick nanorods) as building blocks of photoanodes in DSSC system, rests with their significantly reduced grain boundaries. And investigated the effect of size and morphology with TiO2 NRs on the performance of DSSC. In order to evaluate how the size and shape of NRs affect the competing kinetics and clarify the inherent relationship between the cell performance and the NRs'morphology, photocurrent/photovoltage transient decay techniques were employed to measure the electron transport time (r) and recombination time (?r, also called lifetime). On balance between the optimizations of light-harvesting and charge collection efficiencies, the long-thin NR based film has demonstrated the highest efficiency at 8.87%.These NRs, as building blocks of photoanodes in CdSe QDs sensitized solar cells, are found to be superior to traditionally used TiO2 nanoparticles, which are reflected from the following aspects:(1) the resultant TiO2 mesoporous film possesses wider pore size distribution, which allows higher loading content of QDs and fluent electrolyte diffusion; (2) the as-built quasi-one dimensional network with limited grain boundaries possesses higher electron diffusion coefficient and longer electron lifetime. As a consequence of these, synchronized improvements on photocurrent, photovoltage and fill factor have been achieved, leading to a dramatic elevation of overall solar conversion efficiency. At last, in combination with a highly efficient catalytic counter electrode made of Cu2ZnSnS(Se)4 nanocrystals, the best cell efficiency has reached 5.96%, which is comparable to the best-in-class devices reportedIn this work, TiO2 nanorods (TiO2-NR) based mesoporous film with larger pore distribution and grain boundary-less electron transport network is introduced in perovskite solar cell (PSSC) to replace the traditional one based on TiO2 nanoparticles. Transient photovoltage/photocurrent decays measurements have revealed TiO2-NR based PSSC has much better charge collection efficiency than that of TiO2-NP based PSSC, which leads to improved solar cell performance and reduction of ?-? scan hysteresis. It is the first time that the ?-? scan hysteresis in PSSCs has been correlated to the mesoporous films' morphology and associated with charge collection kinetics. These results suggest the size controlled, one-dimensional TiO2-NRs are superior building blocks of mesoporous film sin PSSCs. |
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