Fabrication Of Two-end-opened TiO₂Nanotubes Array Membranes And Their Application In Quantum Dots Sensitized Solar Cells

TiO2nanotube array membranes have excellent chemical and physical propertiesincluding photostability, chemical stability, non-toxicity, good photoelectric conversionperformance. General speaking, TiO2nanotube arrays are often fabricated by anodizationmethod. As-prepared TiO2nanotubes are attached to the underlying Ti substrate, and theirbottom ends are closed. In this paper, two types of TiO2nanotube, that is, closed-endedand two-end-opened nanotube membrane are fabricated. Raising voltage at the end of theanodization process method is used to prepare two-end-opened TiO2nanotube. XRD,SEM, EDX and TEM are employed to characterize the TiO2nanostructure.Benefiting from the semiconducting nature and distinctive through-hole structure,two-end-opened TiO2nanotube can be used for QDSSCs. Compared to closed-ended TiO2nanotube, this new TiO2nanotube can absorb more quantum dots and improve theefficiency of solar cells. In this paper, successive ionic layer absorption and reactionmethod is used to deposit CdS quantum dots into these two types of nanotube. Forclosed-ended TiO2nanotube, most CdS nanoparticles aggregate at the top surface ofnanotubes and clog the nanopores. In the case of two-end-opened TiO2nanotube, CdSnanoparticles cover not only on the inner wall but also on the outer wall of nanotubesevenly and thus a sandwich-like trilayer CdS/TiO2/CdS heterojunction is formed. Thephotovoltaic parameters of the QDSSC based on the two-end-opened nanotube arraymembrane are as follows: PCE=1.64%, Jsc=4.91mA·cm-2, Voc=0.62V and FF=54.3%.