Doctor-bladed Cu2ZnSnS4 light absorption layer for low-cost solar cell application

The doctor-blade method is investigated for the preparation of Cu2ZnSnS4 films for low-cost solar cell application. Cu2ZnSnS4 precursor powder, the main raw material for the doctor-blade paste, is synthesized by a simple ball-milling process. The doctor-bladed Cu2ZnSnS4 films are annealed in N-2 ambient under various conditions and characterized by X-ray diffraction, ultraviolent/vis spectrophotometry, scanning electron microscopy, and current-voltage (J-V) meansurement. Our experimental results indicate that (i) the X-ray diffraction peaks of the Cu2ZnSnS4 precursor powder each show a red shift of about 0.4 degrees; (ii) the high-temperature annealing process can effectively improve the crystallinity of the doctor-bladed Cu2ZnSnS4, whereas an overlong annealing introduces defects; (iii) the band gap value of the doctor-bladed Cu2ZnSnS4 is around 1.41 eV; (iv) the short-circuit current density, the open-circuit voltage, the fill factor, and the efficiency of the best Cu2ZnSnS4 solar cell obtained with the superstrate structure of fluorine-doped tin oxide glass/TiO2/In2S3/Cu2ZnSnS4/Mo are 7.82 mA/cm(2), 240 mV, 0.29, and 0.55%, respectively.