R. Shankar, K.W. Whites
South Dakota School of Mines and Technology, US
Keywords: conductive ink, solar cell, inkjet, flexible electronics, collector network
Summary:Silver nano-inks are getting popularity for printing various electrode circuits on traditional silicon substrates as well as on flexible substrates. We are particularly interested in inkjet printing of electrodes for next generation solar cells using silver nano-inks. Inkjet printing is a non-contact process which allows minimum wafer damage during the processing. Also, the ability to print narrow features using small drop volumes can allow printing of front contacts and bus bars with minimum shadowing effect. We have produced silver nanoparticles using polyol synthesis and have tailored the ink formulation by choosing a solvent mixture which meets the rheological requirement of industrial printheads (XAAR 1001FF and Trident 256S). A desktop R&D printer LP50 developed by Pix-Dro has been used for the printing optimization for both the printheads. A drop-view camera was used to optimize the inkjet droplets during the jetting process whereas a print-view camera was used to analyze the printed image closely. “Advanced Droplet Analysis (ADA)” software was used to observe the droplet and to study the jetting process.Printing parameters like grayscale (for XAAR 1001FF) or waveform (for Trident 256S), DPI variation, substrate heating etc were optimized to achieve high print quality with sharp edge definition of printed tracks.