Laser-carbonization was conducted with a high-precision laser engraver setup (Speedy 100, Trotec) equipped with a 60 W CO2 laser. Focusing was achieved with a 2.5 inch focus lens providing a focal depth of ~ 3 mm and a focus diameter of 𝑑 = 170 µm. The center wavelength of the laser is 10.6 ± 0.03 µm. The scanning speed 𝜈, generically given in %, was converted into cm•s -1 . The effective output power 𝑃 in watts of the laser was measured with a Solo 2 (Gentec Electro-Optics) power meter. The resulting energy input per area (or fluence) 𝐹 in J•cm -2 in the vector mode onto the film is given by