New insights in the electrodeposition mechanism of CuInse2thin films for solar cell applications

The electrodeposition of CuInSe2, one of the most appropriate absorber for thin layer photovoltaic solar cells, is investigated with a rotating disc electrode by voltametry, steady-state polarization and electrochemical impedance spectroscopy in dilute acidic solutions. Three main potential domains are distinguished. At low cathodic polarizations, binary Cu-Se compounds are deposited. Indium starts to incorporate beyond a potential threshold which is associated with a current peak similar to a passivation peak and with impedance diagrams showing a negative polarisation resistance. For more negative potentials the impedance diagrams exhibit mainly characteristic features corresponding to charge transfer under diffusional control. A reaction path is proposed. These results are discussed in terms of general behavior of multinary compound deposition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)