Enhancing the performance of electrodeposited CuInSe2 solar cells by suppressing secondary phases using sodium dodecyl sulfate

CuInSe₂ thin films were prepared on Mo-coated glass substrates using pulse electrodeposition with an aqueous solution containing sodium dodecyl sulfate (SDS) as an additive. The effect of SDS on the electrochemistry mechanism that inhibits secondary phases (Cu_xSe_y) was examined using cyclic voltammetry, which indicated that SDS can inhibit the reduction of Cu²⁺ and H₂SeO₃ and prohibit the formation of secondary phases. Scanning electron microscopy and atomic force microscopy revealed that the cracks and roughness of CuInSe₂ films decreased considerably after adding SDS into the electrolyte. The suppression of secondary phases was also observed using X-ray diffraction and Raman spectroscopy. The optical bandgap values of the CuInSe₂ films were measured using a UV–vis–NIR spectrophotometer; the bandgap values of the films deposited in the electrolyte with 0 and 1 mM SDS were approximately 0.96 and 1.05 eV, respectively. As expected, based on these differences, the CuInSe₂ solar cell with the Al/AZO/i-ZnO/CdS/CuInSe₂/Mo/glass structure derived from precursor film deposited in an electrolyte containing SDS demonstrated greater efficiency (η = 2.51 %) than that of the cell derived from precursor film deposited in an electrolyte without SDS (η = 0.63 %).