The invention relates to a titanium oxide-based polymer composition. The inventive composition comprises a TiO.sub.x(OH).sub.y(H.sub.2O).sub.z(x+y-+z=3) titanium oxide-based polymer in the form of a gel or sol. Said polymer, which has a one-dimensional (1D) structure, is made from concentrically-wound fibers having a periodicity which is deduced from the spacing between said fibers, of between 3.5 .ANG. and 4 .ANG.. Each fiber comprises TiO.sub.6octahedrons and each TiO.sub.6octahedron shares two opposite edges with two adjacent octahedrons (2.times.2.92 .ANG.) in order to form infinite chains which develop along the axis of a fiber. According to the invention, two adjacent chains form double lines as a result of the shared edges (2.times.3.27 .ANG.). The inventive polymer is suitable for use as a photosensitive element in a photovoltaic cell, such as a sunscreen for a window.