Electrodeposition of CuInSe 2 thin films from aqueous citric solutions II. Investigation of macrokinetics of electrodeposition by means of rotating disk electrode

Abstract

Investigations of the makrokinetics of electrodeposition from citric aqueous solutions containing Cu(II), In(III) and Se(IV) show that the rate of electrodeposition is determined by mixed kinetics (ion mass transfer complicated by a chemical reaction), independent of which compound is formed (CuSe, Cu 3Se 2, CuInSe 2). It was shown that the chemical reaction determining the common rate of electrodeposition is SeO 2− 3 reduction by metallic copper. The reaction constant k = (2.5 ± 0.2)10 −2 cm s −1 was determined experimentally. It was shown that the diffusion stage of CuSe and Cu 3Se 2 formation is determined by the speed of ion mass transfer of Cu(II). When Cu 3Se 2 is formed the possible low surface concentration of copper determined by the slow heterogeneous chemical reaction of Se(IV) reduction by copper is achieved. Over this region of potentials In(III) began to interact with Cu 3Se 2 to produce CuInSe 2. The diffusion stage of this process is determined by the rate of ion mass transfer of Se(IV).