Study of CuInS2/buffer/ZnO solar cells, with chemically deposited ZnS-In2S3buffer layers

Thin film solar cells based on CuInS2/buffer/ZnO have been prepared with different buffer layers of mixed ZnS-In2S3 composition. The buffer films are grown by chemical bath deposition (CBD) from acidic solutions of InCl3, ZnSO4 and thioacetamide (TA). A kinetics study of the growth of the buffer layers is carried out with the quartz crystal microbalance. The influence of bath conditions (solution, temperature and composition) on the growth rate is studied. Films are obtained with different physical, chemical and morphological properties. The absorption coefficient spectra of the films show a variation depending on the CBD conditions, with absorption edges between 2.6 and 3.35 eV. Surface morphology of the films, observed with scanning electron microscopy, reveals that the presence of Zn produces characteristic structures with microtubular form, compared with pure In2S3 buffer films. Solar cell results show a significant increase of Voc and FF upon introducing Zn2+ ion in the buffer layer.