Influence of the thermal annealing on the morphological and structural properties of ZnO films deposited onto polyimide substrates by ink-jet printing

In this work, ZnO films were deposited onto flexible polyimide substrates by ink-jet printing nanoinks containing polyol-synthesized nanocrystals. ZnO films were annealed at 200–400 °C for 10 min and 60 min under the ambient atmosphere. The morphological (shape, size, size distribution, surface roughness), structural (phase composition, crystal structure), optical (band gap, transmission coefficients) properties and the chemical composition of the synthesized nanocrystals and the obtained films were studied. X-ray diffraction analysis, transmission and scanning electron microscopies, atomic force microscopy, Fourier-transform infrared (FTIR) and optical spectroscopies, and energy-dispersive X-ray spectroscopy (EDS) were used to study the properties of obtained ZnO materials. The films, annealed at T a = 400 °C for t a = 60 min, and nanocrystals, synthesized for t g = 120 min, have the good fundamental characteristics for application in the microelectronic devices, especially in solar cells and thermoelectric generators.