Jianqiang Luo

Forest-like TiO2 hierarchical structures for efficient dye-sensitized solar cells

Forest-like TiO2 hierarchical structures are prepared by the acid-assisted hydrothermal method without the use of any template or additive. The performances of dye sensitized solar cells (DSSCs) fabricated with the nanoforest structures are much higher than those assembled with nanorod array films. Crystalline nanorods and nanobranches act as preferential electron pathways for efficient charge collection. Nanobranches filling in the spaces among the nanorods increase the amount of dye-loading and enhance the light-harvesting property. Thus, our photoanode can take advantage of both fast electron transport and high surface area. DSSCs made of nanoforest films with a thin layer of nanocrystalline TiO2 as the adhesive show the maximum energy conversion efficiency. Without any mediator, we can also fix films on FTO glasses through physical effects, which suggests potential applications in flexible solar cells.

Template-free synthesis of hierarchical TiO2 structures and their application in dye-sensitized solar cells.

We demonstrate here the synthesis of a hierarchical TiO(2) architecture without any surfactants or templates. Two kinds of structure existed simultaneously, the ordered nanoarrays at bottom provided direct conduction pathway for photo generated electrons, while the upper micro-flowers consisted of nanobelt as building units increased the light harvesting ability as the scattering part. The formation mechanism of the hierarchical architecture has been proposed by studying the morphology evolution processes upon reaction time. The performance of dye-sensitized solar cells based on the obtained hierarchical anatase TiO(2) has been also studied, giving a J(SC) = 12.44 mA cm(-2), V(OC) = 0.64 V, FF = 69.05%, and η = 5.53%, which is superior than commercial TiO(2) (P25). The UV-vis results prove that the obtained morphology is beneficial to light-scattering and thus increases the light harvesting ability. This hierarchical TiO(2) structure offers great potential for the development of high-efficiency DSSCs.

Fe2O3@SnO2 nanoparticle decorated graphene flexible films as high-performance anode materials for lithium-ion batteries

A flexible graphene film decorated with spindle-like Fe2O3@SnO2 nanoparticles was fabricated through vacuum filtration of Fe2O3@SnO2 and GO mixing solution, followed by thermal reduction. The core–shell structured Fe2O3@SnO2 nanoparticles were synthesized through a facile hydrothermal route, which avoided agglomeration of Fe2O3 and SnO2 nanoparticles and was beneficial for electrolyte diffusion. Microstructure characterizations showed that the spindle-like Fe2O3@SnO2 nanoparticles were uniformly dispersed between layered graphene nanosheets, forming a sandwich-like structure. The unique interleaved structure was favorable for lithium ion diffusion and electron transfer. As binder-free electrodes for lithium-ion batteries, the flexible Fe2O3@SnO2/GS films exhibited discharge and charge capacities of 2063 and 1255 mA h g−1 respectively, with an excellent cycling performance of 1015 mA h g−1 even after 200 cycles. The specific capacity of the Fe2O3@SnO2/GS electrode is higher than that of both Fe2O3/GS and SnO2/GS electrodes, indicating a positive synergistic effect of Fe2O3 and SnO2 on the improvement of electrochemical performance.

A bilayer structure of a titania nanoparticle/highly-ordered nanotube array for low-temperature dye-sensitized solar cells

A chemical-free, environmentally friendly and harmless water immersion method is developed to delaminate anode oxidationtitania nanotube (TNT) arrays from Ti foils to obtain a free-standing TNT membrane. The as-synthesized TNT membrane with tunable thickness which is controlled by anodization time are used in low-temperature dye-sensitized solar cells (DSSCs) as a second layer to improve the DSSC efficiency. Compared with the common titania nanoparticle electrode, a water-delaminated TNT membrane electrode of 16 μm in thickness can significantly enhance the DSSCs photovoltaic performance with a short-circuit current density from 3.87 to 7.63 mA cm−2 and a fill factor from 0.637 to 0.708, which combinatorially lead to a remarkable increment of photo conversion efficiency from 1.70% to 3.68%. The results show that, owing to its vertically aligned ordered nanotube structure, the TNT arrays exhibit trifunctional behavior when used as an electrode, which are charge generation, light scattering and I3− diffusion improvement.