We present a sol-gel process which is used to prepare thin titanium dioxide
nanoparticle layers by spin-coating or doctor-blading techniques. After be
ing sensitized with a dye, the films are used for the transport of electron
s in photoelectrochemical solar cells. The titanium dioxide particles have
diameters of about 100 nm. A comparison with screen-printed layers consisti
ng of particles with a typical size of 25 nm shows that the power conversio
n efficiencies of the cells reach identical levels. Thus, we can show that
a large internal surface of the nanocrystalline layers, which is one prereq
uisite for a good solar cell performance, can only be achieved by adjusting
the respective size of the nanoparticles. The coating and heating processe
s, and the obtained crystal structure of titanium dioxide also play a major
part in the preparation of highly efficient devices. (C) 1999 Elsevier Sci
ence B.V. All rights reserved.