Cu2CoSnS4 thin films as suitable absorber layers for photovoltaic applications, synthesized by spray pyrolysis

Cu2CoSn4 (CCTS) Thin films which belong to the chalcogenide family, were synthesized by spray pyrolysis technique. These films were deposited onto glass substrate heated at 200 degrees C for spray duration 60 min and were annealed in the sulfur atmosphere at 550 degrees C during 30 min. The diffractograms of x-ray diffraction (XRD) prove that the CCTS thin films exhibit the stannite structure with three orientations along (112), (103) and (004) planes. SEM images of CCTS thin films show granular, dense and rough surface. The optical characterization of CCTS thin films has confirmed a high value of absorption coefficient (>10(4) cm(-1)) and direct gap energy equal to 1.72 eV which suggests its use as an absorber layer in the solar cells. Furthermore, the electrical characterization shows that the conductivity of the CCTS thin films is a << p >> type and the activation energy is around 1.05 eV. Moreover, the impedance spectroscopy was used to determine the AC and DC conductivities.