Operando color microscopy and ex situ AFM were used to investigate the lithiation process in pure (a-Si:H) and methylated (a-Si1-x(CH3)x:H) amorphous silicon thin layers. Color analysis of optical images allows for monitoring thickness changes of a-Si:H layers. Unlike pure a-Si:H, the first lithiation of a-Si1-x(CH3)x:H is found to be spatially non-uniform: lithiation starts at a limited number of locations then expands radially, forming circular lithiation spots. The morphology of the lithiation spots and their evolution is accurately measured by ex situ AFM. A mechanism is proposed to explain this phenomenon, involving the high resistivity of methylated silicon and the existence of low-resistance point defects.

Polypyrrole (PPy)-indium phosphide (InP) composite material was electrochemically prepared by the incorporation of InP into a PPy matrix during electrochemical synthesis (cycling) under magnetic stirring from the acetonitrile/LiClO4 electrolyte containing the Py and InP particles. The PPy-InP composite material was designed to explore new approaches to improve light-collection efficiency in polymer photovoltaic. The samples were characterised by cyclic voltammetry, impedance spectroscopy measurement, scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-visible and photoelectrochemical measurements. It was observed that the photocurrent of the composites was higher than that of the single PPy films and increased with InP concentration. The study showed that the presence of InP particles in the polymeric film improves the optical and the photovoltaic properties of PPy and give information on the use possibility of these films for photovoltaic cells' application.

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