Hydrophilic Cu2ZnSnS4 nanocrystals for printing flexible, low-cost and environmentally friendly solar cells

Using Cu2ZnSnS4 (CZTS) nanocrystal-based ink (via a solvothermal route) and roll-to-roll printing, CZTS films are prepared on a Mo-coated Al foil, and then flexible solar cells with a structure of Al foil/Mo/CZTS/ZnS/i-ZnO/ITO/Al–Ni and a power conversion efficiency of 1.94% are constructed, in which all the materials are low-cost and environmentally friendly.