Influence of film properties on the temperature development in powder aerosol deposited CuFeO 2 films during optically induced low temperature posttreatment by high-power LEDs

The powder aerosol deposition method (PAD or AD) is a promising method to produce dense ceramic coatings at room temperature. A variety of functional ceramics can be deposited using this technique, including thermoelectric CuFeO2. However, process-related stresses and lattice deformations occur in deposited films. They may negatively affect their functional properties. A novel approach for restoring the functional properties is irradiation using high-power LEDs. In this work, screen-printed temperature sensors with electrode structure and four-wire substrates were successfully coated with CuFeO2 by aerosol deposition. Post-deposition treatment using high-power LED irradiation resulted in significantly higher annealing temperatures compared to an equivalent setup with a resistive heating element as energy source. In the range from 9 µm to 33 µm, the film thickness had no significant impact on the electrical conductivity after annealing. As a final step, the comparison of LED-based and furnace-based posttreatment revealed that the peak annealing temperature is the decisive parameter that controls the electrical conductivity of the films. These findings highlight the potential of posttreatment via LED as an energy- and time-efficient method for enhancing the electrical conductivity of CuFeO2 AD films and may enable new applications in other fields of aerosol deposition for different film materials.