Inkjet-Printed In Situ Structured and Doped Polysilicon on Oxide Junctions

We investigate the inkjet printing of liquid silicon ink to form in situ doped and structured passivating contacts. The ink consists of neopentasilane oligomers in solvents and decomposes into amorphous silicon with a short anneal. By printing boron- and phosphorus-doped ink on silicon oxide, polycrystalline silicon on oxide (POLO) junctions for both p-type and n-type polarities (POLO²) are formed and the saturation current densities as low as 5 fA/cm 2 are achieved for n + -POLO junctions. We perform a structured printing in interdigitated back contact (IBC) geometry achieving emitter and base fingers with an average finger height of up to 103 nm. The application of inkjet printing allows for a simplification of POLO and POLO 2 solar cell processing. In particular, for POLO 2 -IBC cells, a lean process flow is facilitated.