This work demonstrates the electrodeposition of cuprous oxide (Cu 2 O) thin films onto a fluorine-doped tin oxide (FTO)-coated conducting glass substrates from Cu(II) sulfate solution with C 6 H 8 O 7 chelating agent. During cyclic voltammetry experiences, the potential interval where the electrodeposition of Cu 2 O is carried out was established. The thin films were obtained potentiostatically and were characterized through different techniques. From the Mott-Schottky measurements, the flat-band potential and the acceptor density for the Cu 2 O thin films are determined. All the films showed a p-type semiconductor character with a carrier density varying between 2.41 × 10 18 cm −3 and 5.38 × 10 18 cm −3 . This little difference is attributed to the increase of the stoichiometric defects in the films with the deposition potential. Atomic force microscopy analysis showed that the Cu 2 O thin films obtained at high potential are more homogenous in appearance and present lower crystallites size. X-ray diffraction measurements indicate a cubic structure with good crystallization state and the deposition potential was found to have an influence on the size of the crystallites. The optical measurements show a direct band gap between 2.07-2.49 eV depending on the applied potential.

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Germanium nanocrystals were prepared by a nanocluster source and characterized by photoluminescence and spectroscopic photometry methods. The optical measurements were carried out in order to estimate the effective bandgap of the Ge nanocrystals. Both Mie theory and the quantum confinement theory were applied to interpret the extracted absorption data. We found that the quantum confinement theory enables to explain the nanocrystal size and the host matrix dependence of the nanocrystal bandgap. On the other hand, the photoluminescence measurements have not allowed to confirm the bandgap evaluated from absorption data. This is explained as due to the dominant effect of the recombination at the nanocrystals surface.

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In this work, a new n-type polymer based on a thiazole-diketopyrrolopyrrole unit has been synthesized through direct (hetero)arylation polycondensation. The molar mass has been optimized by systematic variation of the the monomer concentration. Optical and electrochemical properties have been studied. They clearly suggested that this polymer possess a high electron affinity together with a very interesting absorption band, making it a good non-fullerene acceptor candidate. As a consequence, its charge transport and photovoltaic properties in a blend with the usual P3HT electron-donating polymer have been investigated.