Electrochimica Acta, Vol.143, 232-239, 2014
A four-functional composite-hierarchical anatase TiO2 microsphere consisting of nanoparticles, nanowires and submicron ellipsoidal spheres for Dye Sensitized Solar Cells
In this paper, we prepare a composite-hierarchical microsphere (HMS) which is composed of two kinds of HMSs: one flower-like microsphere (FMS, similar to 1.5 mu m, containing nanoparticles and nanowires) and plentiful mesoporous submicron ellipsoidal spheres (ESs, similar to 200 nm, assembled with nanoparticles) which are embedded evenly in the FMS. For comparing, pure FMS and ES are prepared, respectively. It is found that the composite-HMS possesses (a) the highest BET surface area, (b) the highest light scattering ability, (c) the fastest electron transport and the longest electron life time, and (d) light trapping ability enabled by multiple light reflection and scattering between ESs and nanowires inside each FMS*ESs particle. The energy conversion efficiency of 7.91% of the DSSC based on FMS*ESs is higher than devices based on ES and FMS (7.22% and 7.24%, respectively), which also benefits from the structural advantages of the composite-HMS compared with non-composite HMSs. (C) 2014 Published by Elsevier Ltd.
Keywords:Dye sensitized solar cells;Titanium dioxide spheres;Composite-hierarchical microspheres;Electrical transport;Charge recombination