Electrodeposition of CuInSe2 films by an alternating double-potentiostatic method using nearly neutral electrolytes

One step electrodeposition with an alternating double-potentiostatic(DPSED) program was used to prepare CuInSe2 thin films in nearly neutral aqueous electrolytes with sodium citrate complex. Linear sweep voltammetry(LSV) was measured to probe voltammetric properties of electrolytes with respect to Cu, In and Se individual precursor and their mixed solutions. Compositional and structural characteristics of the as-deposited and annealed films at 400 °C in Ar atmosphere for 0.5 h were analyzed by XRD and XPS. The results showed that reduction of Cu2+ to Cu+ at one potential point of −800 mV and subsequently formation of CuIn alloy as well as metal In and amorphous Se at the other potential point of −1400 mV were responsible for synthesis of CISe chalcopyrite. Composition self-regulation made DPSED films have three elements co-deposition and more uniform element distribution, which promoted chalcopyrite CISe formation.