Conductive film by spray pyrolysis of self-reducing copper–silver amine complex solution

• Conductive films were made by spray pyrolysis of a copper–silver complex solution.
• The volume resistivity of the film was decreased by using higher spraying temperature.
• The volume resistivity of the film was decreased by using longer annealing time.
• The volume resistivity of the film was decreased by adding silver.
• The films fabricated on polyimide substrates exhibited higher volume resistivity.

In this work, a facile method was demonstrated to prepare conductive film deposited on glass and polyimide (PI) substrates using spray pyrolysis of a copper–silver complex solution in nitrogen atmosphere. The copper–silver amine complex solution was prepared by mixing together the copper(II) acetate monohydrate, silver oxide, ammonia solution and di-ethanolamine. Four-point probe analysis, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were employed to investigate the properties of the conductive film obtained. The effects of various parameters including spray pyrolysis temperature, molar ratio of copper to silver, type of substrate and annealing time were investigated. The volume resistivity of the film was decreased by using either higher spraying temperature or longer annealing time. In addition, the volume resistivity was also decreased by adding silver. At spray pyrolysis temperature 200 °C and annealing time 25 min. The conductive film with volume resistivity of 19.0 μΩ cm, which is 11 times higher than the resistivity of bulk copper, could be fabricated using molar ratio of copper to silver 0.8:0.2 on glass substrates. Copper oxide was not observed on the film deposited on the glass substrates. In contrast, the film deposited on the PI substrates contained copper oxide and exhibited resistivity 5 times higher than that deposited on the glass substrates.