Copper-based chalcogenide ternary compounds are promising materials to be used as absorber layer in solar cells. In this work, we have reported the preparation of copper antimony sulfide (CAS) thin films by annealing chemically deposited multi-stack of Sb 2 S 3 -CuS and the effect of thickness ratio between two binary sulfides on the formation of different crystalline phases of Cu-Sb-S system. A series of multilayer structure was prepared with different thickness of CuS in order to study the effect of copper concentration on the structural, morphological, optical, and electrical properties of the resulting Cu x Sb 1-x S y films. The CAS films were characterized by several techniques such as X-ray diffraction, Raman scattering, UV-visible spectroscopy, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, andHall effect measurements to evaluate their physical properties. The formation of either pure chalcostibite (CuSbS 2 ) or mixed ternary phases containing chalcostibite, famatinite (Cu 3 SbS 4 ), and tetrahedrite (Cu 12 Sb 4 S 13 ) were detected depending on the thickness ratio of Sb 2 S 3 and CuS. Chalcostibite films revealed desired optical and electrical values. Finally, solar cell was fabricated using the heterostructure FTO/CdS/CuSbS 2 /Ag and characterized by currentvoltage, capacitance-voltage, and impedance-spectroscopy measurements achieving a promising~0.8% efficiency with V OC = 0.484 V, J SC = 5.97 mA/cm 2 , and FF =27.34%. Impedance measurements revealed a low series resistance in the optimal solar cell, as a result, an increment in open circuit voltage.
Novelty StatementThe novelty of this work is the fabrication of CuSbS 2 thin films by tuning the thickness ratio of binary sulfides in Sb 2 S 3 -CuS stack followed by proper thermal annealing. Furthermore, impedance spectroscopic studies of CuSbS 2 solar cell are still lacking; the present study may provide important physical insight to understand the device performance and possibilities toward any further improvement.