Photoelectrochemical study of zinc oxide (ZnO) thin films on different polymer substrates by sputtering technique

This paper investigates the properties of 100-nm ZnO thin films prepared by radio frequency (RF) sputtering technique on polyethylene terephthalate (PET) and polyimide (PI) plastic substrates using X-ray diffraction (XRD) patterns to show the proper formation of hexagonal ZnO (002) structure, with ZnO on PET plastic substrate recording higher peak and FWHM compared to ZnO on PI plastic substrate. AFM reveals smooth surface morphologies on both substrates with a root-mean-square (RMS) roughness of below 10 nm. Optical transmittance measures values exceeding 80% in the visible and infrared (IR) regions on each substrate. ZnO on PET records 3.33 eV, and ZnO on PI measures 3.35 eV of optical band gap ( E g ) from the Tauc plot. The photoelectrochemical cell (PEC) parameter measurement study shows that ZnO thin films on PET and PI plastic substrates have efficiencies ( η = 0.93) and ( η = 0.88), respectively.