Cu2ZnSnS4 precursor ink for spin coating deposition technique

Thin photovoltaics based on chalcopyrite film, Cu(In,Ga)Se2 (CIGS) and related alloys, have exhibited so far efficiency over 22,3% on the laboratory scale. However, the CIGS solar cells scale-up is expected to be hampered because of the low availability of In and Ga in the Earth crust. The most promising next leader in the chalcogenide thin film technology seems to be the kesterite compound Cu2ZnSnS4 (CZTS), as it is based on earth-abundant elements and it shows the better results when low-cost solution processable techniques are employed in the fabrication. Solution-processed inorganic semiconductors, in fact, offer a rising route for the low-cost mass production of solar cells. In this contest, we fine tune the precursor-solution, sustained by means of the Electron Paramagnetic Resonance and Raman spectroscopy, for proposing a stable kesterite precursor ink, which does not require sulphur addiction to complete the phase formation. The high-quality CZTS thin films, obtained by spin coating deposition onto fluorine doped tin oxide coated glass, were characterized by means of Raman spectroscopy, X-ray diffraction and scanning electron microscopy equipped for energy-dispersive spectroscopy. Preliminary devices have been tested.