Electrodeposition of Bi2Te3 thin films onto FTO substrates from DMSO solution

We report the pulsed electrodeposition (PED) of Bi2Te3 thin films from TeCl4 and Bi(NO3)(3) precursors dissolved in dimethylsulfoxide (DMSO) onto SnO2:F coated glasses (FTO) and CdTe/FTO substrates. Results of a detailed set of chronoamperometric experiments allowed us to simulate the corresponding experimental j/t transients through their fitting with different possible contributions involved in the nucleation-growth mechanisms (NGMs) of the Bi2Te3 phase. From this information it was possible to employ a set of potential/time step programs intended to select those resulting in adherent good quality thin films. AFM and SEM micrographs exhibited complete substrate coverage whereas EDX analysis gave Bi/Te ratios close to the expected stoichiometry. High-resolution X-ray diffraction analysis showed that the films were grown in the trigonal phase without the presence of other phases. From electrochemical impedance spectroscopy measurements it was possible to establish the n-type conductivity of the films which was further confirmed by photoelectrochemical experiments. Results open the possibility of using electrodeposited Bi2Te3 thin films instead of copper as back contact in CdTe based photovoltaic solar cells.