*3.1. PIAD Film Deposition*

All samples were prepared in a Bühler Syrus LCIII deposition plant at Fraunhofer IOF using an electron-beam gun HPE6 and Ti3O5 as starter material. A target layer thickness of 200 nm was controlled by quartz crystal monitoring. For characterization, two different fused silica substrates (spectrophotometric characterization: Diameter 25 mm, thickness 1 mm; direct absorption measurement: Rectangular block 20 <sup>×</sup> <sup>20</sup> <sup>×</sup> 6 mm3) located in adjacent positions with identical radial positions in the rotating substrate holder, as well as silicon wafers, were used. During layer growth, additional energetic particle bombardment by means of a Bühler Advanced Plasma Source APS pro was accomplished. For this, two gas fluxes, Γ<sup>1</sup> and Γ<sup>2</sup> (for either argon or xenon as an inert gas), were used. In all experiments, the oxygen flow Γ<sup>3</sup> was 15 sccm, and the substrate temperature was around 110 ◦C. Additional main deposition parameters are summarized in Table 3.

**Table 3.** Main deposition parameters for the plasma ion-assisted evaporation (PIAD) preparation of the titanium dioxide single-layer coatings.

