Self-Organization of TiO₂Nanoparticles in Thin Films

Abstract

Nanocrystalline titanium dioxide colloids have been synthesized using a sol-gel technique followed by growth under hydrothermal conditions in a basic environment at temperatures between 190 and 270 °C. Thin films have been made from aqueous suspensions of these colloids. X-ray analysis showed the colloids to be primarily the anatase crystal phase. Scanning electron microscopy (SEM) revealed a predominantly rodlike particle morphology after growth at lower temperatures and the formation of principally truncated tetragonal or tetrahydral bipyramidal nanocrystallites following growth at higher temperatures. The rodlike particles self-organize into regular cubic arrays with the long axis of the rods aligned perpendicular to the film surface. This self-organization is dependent upon the base used in colloidal synthesis and also upon the dielectric constant of the medium used during film formation.

Low temperature crystallisation of mesoporous TiO2

“…These electrochemical devices require an electron-conducting network with pores on the 10-nm length scale. The nanoarchitecture can be generated by a variety of synthetic routes 9 , among which the sintering of random packed nanoparticles is most widely used 10 . An alternative route with higher morphological control is the structure-directing of inorganic material by supramolecular self-assembly.…”

“…The conversion of the carbon-rich polymer into a sturdy carbonaceous support under an inert atmosphere is a powerful method to further raise the crystallisation temperature to 1000 • C 16 . Thus, in contrast to the nanoparticle approach 10 , supramolecular co-assembly provides structural stability at extremely high temperatures and therefore leads to the growth of large crystallites and greatly improved charge transport properties 15,17 .…”

Improved conductivity in dye-sensitised solar cells through block-copolymer confined TiO2crystallisation

“…5 Traditionally, mesoporous TiO 2 is obtained by sintering a random network of 10-20 nm sized particles which are derived by sol-gel chemistry. 6 The high surface area of these films is decisive for interface sensitive applications. Other important material properties include a large electronic band-gap, long-term stability against corrosion and a high surface affinity for dyes.…”

Photovoltaic Characteristics of a Dye-Sensitized Solar Cell (DSSC) Fabricated by a Nano-Particle Deposition System (NPDS)

“…TiO 2 layers formed by this paste approach, however, require numerous time-consuming steps. 10) To overcome these issues, dry TiO 2 powders have been deposited on a rigid glass substrate. According to the studies done by S.Q.…”