Impact of Ink Synthesis on Processing and Properties of Inkjet-Printed Silicon Thin Films

E. Drahi, A. Gupta, S. Blayac, L. Lombez, M. Jubault, P. Benaben
Ecole Nationale Supérieure des Mines de Saint Etienne, FR

Keywords: silicon, nanoparticles, inkjet-printing, photovoltaics, thermoelectric

Summary:

Inkjet printing has a high potential for cost reduction in solar cell and thermoelectric industry. This study demonstrates that silicon thin films can be produced by inkjet-printing of a silicon ink followed by consequent drying and annealing steps. Surface preparation of the substrate and adapted drying process are crucial for thin film homogeneity and continuity. Control of the annealing step is linked with the microstructure control. Evolution of coalescence step is monitored by scanning electron microscopy and evaluated quantitatively by Raman microscopy. While denser and more crystalline layers are obtained, cracks appear within thin film and substrate because of stress provoked by oxidation of the surface. Electrical conductivity is improved with higher annealing temperature until a threshold where both physical degradation and oxidation of the layers limits strongly the carrier transport phenomenon. In opposition transmission of the thin films is altered with increasing annealing temperature. Evolution of the thermal conductivity is performed by Raman spectroscopy and can be tailor in a large range between ~1 to ~100 W/mK. Therefore control of the microstructure evolution along with applied annealing process allows tailoring of optical and electrical properties.