Influence of strain/stress on the nonlinear-optical properties of sprayed deposited ZnO:Al thin films

International audienc

Magnetic nanoconstrictions made from nickel electrodeposition in polymeric bi-conical tracks: Magneto-transport behavior

International audienceSingle nanoconstriction per magnetic wire is obtained by bi-conical track etching and electrodeposition. Magnetoresistance measurements at various angles result in irreversible jumps. Resulting jumps of magnetization have been attributed to the pinning and depinning of a constrained magnetic domain wall. a b s t r a c t In a cylindrical magnetic nanowire, a magnetic domain wall (DW) can move along the wire when an applied magnetic field or a spin-polarized current is applied. We show that in a magnetic device composed of two conical nanowires connected by a nanosized constriction, a DW can be trapped and detrapped. The magnetoreistance and the relaxation processes of the DW exhibit a specific behavior. Such a device has been fabricating by Ni electrodeposition in bi-conical tracks polymer membrane made of Swift Heavy Ions bombarded poly(VDF-co-TrFE) copolymer and poly(ethylene terephtalate) PET thin films. The latter method allows to monitor the conicity of the bi-conical wires and to give access to a panel of very well-defined structures.

Indium free electrode, highly flexible, transparent and conductive for optoelectronic devices

WO3/Ag/WO3 multilayer structures were used as ITO free transparent electrode, transparent heat mirrors and transparent heaters. WO3/Ag/WO3 stacked layers were deposited by sequential sublimation, evaporation under vacuum. After optimization of Ag thickness (16 nm), they exhibit low sheet resistance (8 Ω/sq), high transmittance in the visible (TMax = 91.5%, averaged T400-700 = 80.6%) and high reflection in the near infrared and infrared regions. These values are optimal when it is used as transparent electrode but, as transparent heat mirrors 18 nm are better due to higher reflection in the NIR and IR. All these properties made possible to use them in different devices. When used as transparent anode in organic photovoltaic cells, they allow achieving performance similar to those obtained with ITO. Their transmission and reflection spectra show that they can also be employed as transparent heat mirrors. Similarly, studies dedicated to heating properties of the WO3/Ag/WO3 multilayer structures show that their performance are comparable to those obtained with another possible substituent to ITO, silver nanowires thin films

Assessing the suitability of copper thiocyanate as a hole-transport layer in inverted CsSnI3 perovskite photovoltaics

We report the fndings of a study into the suitability of copper (I) thiocyanate (CuSCN) as a hole-transport layer in inverted photovoltaic (PV) devices based on the black gamma phase (B-γ) of CsSnl3 perovskite. Remarkably, when B-γ-CsSnI3 perovskite is deposited from a dimethylformamide solution onto a 180–190nm thick CuSCN flm supported on an indium-tin oxide (ITO) electrode, the CuSCN layer is completely displaced leaving a perovskite layer with high uniformity and coverage of the underlying ITO electrode. This fnding is confrmed by detailed analysis of the thickness and composition of the film that remains after perovskite deposition, together with photovoltaic device studies. The results of this study show that, whilst CuSCN has proved to be an excellent hole-extraction layer for high performance lead-perovskite and organic photovoltaics, it is unsuitable as a hole-transport layer in inverted B-γCsSnI3 perovskite photovoltaics processed from solution

3C-SiC enhances the GaN HEMT

International audienc

On the contribution of fullerene to the current of planar heterojunction organic solar cells

International audienceRecently, significant progress in the field of organic photovoltaic cells was obtained by substituting new electron acceptor molecules to the fullerene, which was attributed to the fact that the fullerene absorption is quite small. Nevertheless, we demonstrate in the present work that, in the case of inverted cells, i.e. when the transparent bottom electrode is used as cathode, the contribution of fullerene to the Jsc short-circuit current of the cells, if not dominant, is not negligible; and that mainly in the short wavelength spectral range. The experimental results are confirmed by an optical simulation. Due to this significant contribution to Jsc, the light transmission of the transparent electrode towards the UV-part of the spectrum is crucial for inverse cell performances. When a transparent conductive electrode based on an alternative dielectric/metal/dielectric structure is substituted to ITO, such as ZnS/Ag/TiO 2 , the study allows to obtain promising results, although there is a loss of performance due to the decrease of transmission of TiO 2 below 400 nm in wavelength

Stabilisation of the electrical and optical properties of dielectric/Cu/dielectric structures through the use of efficient dielectric and Cu:Ni alloy

International audienc