Polymer metal oxide composite layers for optical functional coatings

The objective of this work was to prove the suitability of metal oxide polymer composite layers for optical functional coatings. Because of their flexibility such layers could better meet the mechanical requirements of flexible substrates such as plastic foils than conventional dielectric coatings. Furthermore, with organic film components it should be possible to integrate specific layer properties like hydrophobicity or other functionalities. Thin composite layers of ditantalum pentoxide (Ta2O5) and polytetrafluoroethylene (PTFE) were made by a co-sputter deposition process. The Ta2O5 films were coated with reactive DC magnetron sputtering in an Ar/O2 atmosphere. For the PTFE films a PTFE target with RF power input was used. The influence of process parameters (power, gas atmosphere) on the optical and mechanical layer properties (transmittance in the visible range, dispersion, infra red absorption, adhesion, crack onset strain) was investigated. In addition different optical layer systems based on conventional material combinations and on polymer composites were compared.