Modified crystal quality of Cu(In,Ga)Se2 solar cells: Elimination of island-shaped indium layer by pulse current electrodeposition method

Highlights: • Flat and uniform In film was deposited on Mo/Cu substrate by pulse current electrodeposition method. • Island-shaped surface morphology of In film was eliminated. • Concentration polarization and 3D island growth were controlled successfully. • 10.78% CIGSe solar cell was fabricated. The island-shaped surface morphology of electrodeposited In film is one of the major obstacles to improve the efficiency of Cu(In,Ga)Se₂ (CIGSe) solar cells, which detrimentally affects the composition and thickness uniformity of the stacking Cu/In/Ga precursors and absorbed layers. In this study, pulse current electrodeposition method was used to deposit smooth and uniform In film on Mo/Cu substrate. Flat In film with smooth surface and compact structure was deposited with pulse current density j ≥ 62.5 mA cm⁻², pulse frequency f ≥ 1000 Hz, and duty cycle γ = 25%. CIGSe absorber films with flat surface and large grains were prepared by selenizing the stacking metal layers deposited by pulse current method. Finally, the CIGSe solar cell with conversion efficiency of 10.78% was fabricated based on the smooth In films, which was better than that with island-shaped non-uniform In films.