Developing solar cell front contacts using an all inkjet printing process following the selective emitter approach

We present an approach for complete inkjet printing of solar cell front contacts for the implementation of "selective emitter approach", which can help in solar cell efficiency improvement. The fabrication of optimized emitters that can allow the low recombination below the silver front contact is an important process in solar cell fabrication. This selective emitter approach presents a heavily doped layer beneath the electrode and lightly doped regions between the electrode grids. Selective opening of the anti reflection coating is needed to implement this combination of heavily and lightly doped regions. This was achieved using an inkjet approach by printing an etchant-dopant ink followed by the printing of a diffusion barrier using a dielectric ink. Using a Trident Jet256S industrial printhead we created etched pattern with etch width -50 μm. Once this pattern was created, the metallic front contact grid was printed using a silver nano-ink on top of the etched regions. Inkjet printed silver front contact grid with line width -75 μm was printed successfully.