Papers by Author: O. Volobujeva

Abstract: The aim of the current research was to study regularities of chemical bath deposition (CBD) of tin sulphide thin films as function of tin and sulphur concentrations in the solutions. SnS thin films were deposited onto Mo-, ITO-and TO-coated glass and onto borosilicate glass substrates at room temperature for 24 hours. The concentrations of sulphur and tin (ratio 1:1) in the deposition solution were varied from 0.01 M to 0.09 M. Films were characterized by SEM and Raman spectroscopy. The structuraly best tin mono-sulphide films with good adhesion to the substrate were deposited at concentration of consituents in solution 0.03M. The films deposited at concentration of 0.01M had non-uniform and incomplete coverage of the surface on all used substrates whereas at tin and sulphur concentrations of 0.05M and higher films were peeling off of the substrate.

Abstract: Thin films of Cu-In-Se (CISe) photoabsorber with overall composition of CuIn3Se5 were deposited onto glass/ITO substrates by using physical vapour deposition (PVD) technique. Thermal conditions for the substrates during deposition process and following thermal annealing were selected with the purpose to prepare polycrystalline n-CuIn3Se5 photoabsorber layers for the hybrid photovoltaic structures based on inorganic photoabsorber and conductive polymer functional layers. It was found, that the CISe layers deposited at the temperature of substrate of 200 °C and annealed at the temperature range of 450-500 oC in vacuum and double annealed in argon and vacuum at 500 oC demonstrate high photosensitivity and photoconductivity under white light illumination of 100 mW/cm2 intensity. Obtained results show the chalcopyrite structure of prepared photoabsorber films with good adhesion to the glass/ITO substrate.

Abstract: This paper reviews results of studies on different materials and technologies for polycrystalline solar cells conducted at Tallinn University of Technology. Structural properties and defect structure of kesterite CZTS compounds (Cu2ZnSnSe4, Cu2ZnSn(SSe)4) were studied. Influence of selenization parameters of a Zn-Cu-Sn stacked layer on the CZTS layer growth and on the morphology, distribution of elements was analyzed. All the results obtained have been used to optimize the technology of producing solar cell structures in different designs. Cu2ZnSnSe4 and, Cu2ZnSn(SSe)4 based monograin layer solar cells were developed.