Synthesis of hierarchical TiO2 nanowires with densely-packed and omnidirectional branches.
In this study, a hierarchical TiO2 nanostructure with densely-packed and omnidirectional branches grown by a hydrothermal method is introduced. This morphology is achieved via high-concentration TiCl4 treatment of upright backbone nanowires (NWs) followed by hydrothermal growth. Secondary nanobranches grow in all directions from densely distributed, needle-like seeds on the jagged round surface of the backbone NWs. In addition, hierarchical, flower-like branches grow on the top surface of each NW, greatly increasing the surface area. For dye-sensitized solar cell (DSSC) applications, the TiO2 nanostructure demonstrated a photoconversion efficiency of up to 6.2%. A parametric study of the DSSC efficiency showed that branched TiO2 DSSCs can achieve nearly four times the efficiency of non-branched TiO2 nanowire DSSCs, and up to 170% the efficiency of previously-reported sparsely-branched TiO2 NW DSSCs.
Department of Mechanical Engineering, University of California, Berkeley, CA 94720-1740, USA. cgrigoro@berkeley.edu.
Daeho
D
Lee
Yoonsoo
Y
Rho
Frances I
FI
Allen
Andrew M
AM
Minor
Seung Hwan
SH
Ko
Costas P
CP
Grigoropoulos