CIGS Thin Film Solar Cells by Electrodeposition

Electrodeposition Fabrication of Chalcogenide Thin Films for Photovoltaic Applications

Electrodeposition, which features low cost, easy scale-up, good control in the composition and great flexible substrate compatibility, is a favorable technique for producing thin films. This paper reviews the use of the electrodeposition technique for the fabrication of several representative chalcogenides that have been widely used in photovoltaic devices. The review focuses on narrating the mechanisms for the formation of films and the key factors that affect the morphology, composition, crystal structure and electric and photovoltaic properties of the films. The review ends with a remark section addressing some of the key issues in the electrodeposition method towards creating high quality chalcogenide films.

Controllable Growth of Ga Film Electrodeposited from Aqueous Solution and Cu(In,Ga)Se2 Solar Cells

Electrodepositon of Ga film is very challenging due to the high standard reduction potential (-0.53 V vs SHE for Ga³⁺). In this study, Ga film with compact structure was successfully deposited on the Mo/Cu/In substrate by the pulse current electrodeposition (PCE) method using GaCl₃ aqueous solution. A high deposition rate of Ga³⁺ and H⁺ can be achieved by applying a large overpotential induced by high pulse current. In the meanwhile, the concentration polarization induced by cation depletion can be minimized by changing the pulse frequency and duty cycle. Uniform and smooth Ga film was fabricated at high deposition rate with pulse current density 125 mA/cm², pulse frequency 5 Hz, and duty cycle 0.25. Ga film was then selenized together with electrodeposited Cu and In films to make a CIGSe absorber film for solar cells. The solar cell based on the Ga film presents conversion efficiency of 11.04%, fill factor of 63.40%, and V_oc of 505 mV, which is much better than those based on the inhomogeneous and rough Ga film prepared by the DCE method, indicating the pulse current electrodeposition process is promising for the fabrication of CIGSe solar cell.