A one-step method to prepare carbon and dielectric composited films featuring a skeleton-skin structure

A one-step and cost-efficient strategy to prepare carbon and dielectric composites with a skeleton-skin structure by a sol-gel method has been proposed. For the model system in the present work, i.e. C-TiO2 composite films, the insight of the wet chemical mechanisms in sols was illustrated by the electrical compensation theory. The structure and carbon crystallization evolutions with annealing process were investigated, demonstrating the nano carbon with an average sp2 cluster size ranging from 1.1 nm to 1.4 nm. The resultant composite films turn out to be rutile TiO2 skeleton covered by carbon with intimate interfaces. Benefited from this firm composite structure containing nano carbon, the film possesses tunable and outstanding electrical and optical performance. By appropriate handling annealing temperature, the film could present a high extinction coefficient qualified for solar selective absorber, or show a relatively low extinction coefficient and resistivity (about 10−2 Ω cm).