Cobalt ferrite (CoFe2O4) nanoparticles (NPs), with an average diameter of about 4-10 nm, were produced by the proteic sol-gel method and successfully doped into the active layer of poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) organic solar cells. Pristine and CoFe2O4 NPs-doped blends of P3HT:PCBM were dispersed in a mixture of o-xylene:tetralin (1 mg/mL) based non-halogenated solvents and deposited via a semi-industrial blade coating process on flexible substrates to fabricate large area (0.55 cm2), flexible organic solar cells with inverted configuration. The main focus of this study aims to assess the influence of NPs on the efficiency, stability and lifetime of the produced devices. From the photovoltaic parameters it was observed that the optimization of the bulk-heterojunction through the incorporation of CoFe2O4 NPs resulted in increased short-circuit current density. As a result, the power conversion efficiency of doped devices increased by 10 % when compared with the undoped reference devices. Tests of lifetime and stability were performed using International Summit on OPV Stability (ISOS) protocols ISOS-D-3, ISOS-O-1 and ISOS-L-1. For the duration of the tests (1200 h), the results showed that doped cells presented performances at least comparable with those of reference cells.

Mӧssbauer spectroscopy, X-ray diffraction and hardness measurements were used to investigate the atomic redistribution and phase transformation of solution-treated and 440°C aged Maraging-300 steel specimens. The ageing temperature that resulted in the best mechanical properties in this steel was 480ºC. At 440ºC, the formation of the precipitates that assure excellent mechanical properties of the maraging steel (Ni3Ti, Fe2Mo) was not expected. The results indicated that Mo and Ti redistribution was severe during the first hour of ageing. The mobility of the Ni atoms probably occurred during all stages of the ageing process, and the Co atoms remained close to Fe atomic sites. An irregular behaviour of the formation of paramagnetic phases containing iron was observed, and some evidence of the formation of these phases without Fe will be discussed. The formation of metastable phases was suggested and the possibility of austenite reversion was not discarded at this ageing temperature.

Amongst the many parts of a silicon cells photovoltaic module, silicon is the most important and expensive constituent. Thus, research on silicon recycling from damaged cells can lead to economic and environmental benefits. In this work, the broken silicon cells were tailored to function along with the fluorine-doped tin oxide as the transparent electric conductors. The broken silicon cells were analyzed by the current density versus voltage plots, together with the Mott-Schottky, X-rays diffraction and fluorescence analysis. Under light, the damaged cells sandwiched between the two transparent electric conductors presented photovoltaic effect. However, such effect was not obtained after the removal of the antireflection layer due to the destruction of the n-type layer as demonstrated by the Mott-Schottky analysis. The X-rays diffraction revealed samples rich on silicon atoms and the presence of aluminum atoms as impurity.