The preparation of ultra-thin semi-transparent solar cells with potential applications in windows or transparent roofs entails several challenges due to the very small thickness of the layers involved. In particular, problems related to undesired inter-diffusion or inhomogeneities originated by incomplete coverage of the growing surfaces must be prevented. In this paper, undoped SnO2, CdS, and CdTe thin films with thickness suitable for use in ultra-thin solar cells were deposited with a radiofrequency (RF) magnetron sputtering technique onto conductive glass. Preparation conditions were found for depositing the individual layers with good surface coverage, absence of pin holes and with a relatively small growth rate adapted for the control of very small thickness. After a careful growth calibration procedure, heterostructured solar cells devices were fabricated. The influence of an additional undoped SnO2 buffer layer deposited between the conductive glass and the CdS window was studied. The incorporation of this layer led to an enhancement of both short circuit current and open circuit voltage (by 19 and 32%, respectively) without appreciable changes of other parameters. After the analysis of the cell parameters extracted from the current-voltage (I-V) curves, possible origins of these effects were found to be: Passivation effects of the SnO2/CdS interface, blocking of impurities diffusion or improvement of the band alignment.

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In this work, we present the preparation of CdS nanowires (CdS NWs) using the chemical vapor deposition technique and bismuth (Bi) nanoparticles as catalysts. The obtained nanowires were found to be in the hexagonal Greenockite structure according to XRD diffractograms and Raman spectroscopy measurements. Depending on the growth temperature, two kinds of morphologies were observed in SEM images. At low temperature (around 150 • C), a high density and homogeneous population of thin and straight nanowires grown through the vapor-liquid-solid mechanism was observed. At higher temperature (around 270 • C), thicker bunches of braided nanowires were observed. A quantitative analysis of the temperature-dependent photoluminescence spectra of the CdS NWs was carried out.

In this work, CdS nanowires (NWs) were prepared by the vapor-liquid-solid (VLS) method using Au catalytic nanoparticles (NPs) deposited on different substrates. Scanning and transmission electron microscopy techniques (SEM, TEM) allowed observing NWs with different morphologies: long NWs with lengths of several microns, networks and pointed NWs. Nanotubes were also observed when CdS substrates were used. Possible growth mechanisms are considered for each different morphology. NWs also shown very brilliant photo-luminescence (PL), even at RT. PL spectra is studied as a function of temperature to determine their properties and the origin of the different peaks.

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