Ultrasonic spray coating of kesterite CZTS films from molecular inks

Kesterite Cu 2 ZnSnS 4 (CZTS) has emerged as a potential alternative absorber for thin-film solar cells (TFSCs) and tandem applications owing to their earth-abundant, non-toxic materials and suitable direct bandgap (1.5 eV). This work reports the synthesis of CZTS molecular inks and subsequent deposition by ultrasonic spray coating. Clear and stable molecular inks of CZTS are synthesized with methanol as a solvent in a controlled environment. Characterization of the deposited material revealed smooth, homogeneous and compact films of pure single phase p-type kesterite, with an energy bandgap of 1.52 eV and activation energy of 44 meV. Fabrication of photovoltaic (PV) functional layers via ink-based deposition have the potential to bring down costs and allow sustainable growth of the technology.