Copper sulfide thin films of 75 nm and 100 nm thickness were coated on Kapton foils (PI) of 25 nm thickness by floating them on a chemical bath. The foils were annealed at 150°C-400°C in N 2 converting the coating from CuS to Cu 1.8 S . The sheet resistance of the annealed coatings (100 nm) is 10-50 ohms/square which is almost unaltered after immersion in dilute HCl for 30-120 min. The infrared reflectance predicted for the coatings is 67%-77% at a wavelength 2.5 μm, which is nearly what is experimentally observed. The coated PI has a transmittance (25-35%) peak located around 550-600 nm. These thermally stable conductive coatings on PI foils might be used as conductive substrates for optoelectronic device structures.
Correlation of film thickness to optical band gap of Sol-gel derived Ba0.9Gd0.1TiO3 thin films for optoelectronic applications