Jean Christian Bernède

MS2 (M = W, Mo) photosensitive thin films for solar cells

Abstract Photosensitive textured WS2 and MoS2 films can be obtained by the techniques of reactive sputtering and solid state reaction, as long as the substrates used are each coated with a 10–20 nm Ni layer. When MS2 (M = W, Mo) layers are deposited onto these substrates and then annealed for half an hour at 1073k in an argon atmosphere, textured films crystallized in the 2H-MS2 structure are obtained, with their c crystallite axes perpendicular to the plane of the substrate. The films are nearly stoichiometric. The crystallinity enhancement of the films can be attributed to an improvement in the crystallization process related to liquid NiS phases present at the grain boundaries during annealing. Residual phases (NixSy; Ni;…) are distributed at the grain boundaries and do not strongly disturb the properties of the WS2 and MoS2 films. The optical absorption spectra are similar to those of single crystals, and the high photosensitivity of the films is attributed to a grain size enhancement by the NiS phase.

MoO3/Ag/MoO3 anode in organic photovoltaic cells: Influence of the presence of a CuI buffer layer between the anode and the electron donor

MoO3/Ag/MoO3 (MAM) multilayer structures (layers thickness 20 nm/10 nm/35 nm) are used as anode in CuPc/C60/Alq3/Al organic photovoltaic cells. The averaged transmittance (400 nm-800 nm) of these MoO3/Ag/MoO3 multilayer structures is 70% ± 2% and their sheet resistance is 3.5 ± 1.0 Ω/sq. When these multilayer structures are used as anode, the power conversion efficiency of the MoO3/Ag/MoO3/CuPc/C60/Alq3/Al cells is around 1%, this efficiency is increased of 50% when a thin CuI film (3 nm) is introduced at the interface between the anode and the organic film. This improvement is attributed to the templating effect of CuI on the CuPc molecules.

Organic Solar Cells Performances Improvement Induced by Interface Buffer Layers

J. C. Bernede1, A. Godoy2, L. Cattin1, F. R. Diaz3, M. Morsli1 and M. A. del Valle3 1Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 2Facultad Ciencias de la Salud, Universidad Diego Portales. Ejercito 141. Santiago de Chile 3Facultatd de Quimica, PUCC, Casilla 306, Correo 22, Santiago, 1France 2,3Chile

Synthesis of polymeric thin films by electrochemical polymerization of 1-furfuryl pyrrole: Characterization and charge injection mechanism

The polymeric thin film was synthesized by electrochemical polymerization of 1-furfuryl pyrrole on indium tin oxide (ITO) substrates in aprotic organic media. The cyclic voltammograms and DFT calculations indicate that the electrochemical polymerization process would involve pyrrole rings, although oxidation of the furane ring could also take place. The organic thin films were physicochemically characterized by scanning electron microscopy, electron probe microanalysis, and X-ray photoelectron spectroscopy. The surface morphology has shown that the polymer deposition process has high coverage efficiency. The polymeric layer is very thin with an approximate thickness of 150 nm. When the direct bias is applied to the device, the behaviour is ohmic at low voltage; but once an appropriate value is reached, the current begins to increase exponentially. The current-voltage (I-V) curves exhibit rectifying behaviour with a turn-on voltage at 0.70V. The ideality factor n values found are 9-15, indicating disagreement with the model of a standard Schottky contact.The charge injection mechanism in this device was attributed to the tunnelling effect

Organic solar cells using a multilayer structure MoO3/Ag/MoO3 as anode

Abstract MoO3/Ag/MoO3 structures have been grown and characterized. It is shown that the transmittance of the films increases when the silver thickness increase from 8 to 10 nm, whereas further increase induces transmittance decrease. The study of the variation of the conductivity vs. Ag thickness shows that the MoO3/Ag/MoO3 structures become highly conductive when the Ag thickness reaches 10 nm. Therefore, the optimum structure is obtained when the silver thickness is 10 nm. These MoO3/Ag/MoO3 structures have been used as anode in glass/anode/CuPc (35 nm)/C60(40 nm)/Alq3 (9 nm)/Al (120 nm) organic solar cells. These anodes permit achievable promising results, even if their efficiencies stay slightly smaller than that achieved with ITO based devices.

The lithium effect on the blue and red emissions of Er-doped zinc oxide thin films

Lithium- and erbium-codoped zinc oxide thin films have been successfully deposited on heated glass substrates using the spray pyrolysis technique. This study is an investigation of the Li effect on the enhancement of cathodoluminescent intensity on Er-monodoped ZnO films. Crystallinity, morphology and luminescence characteristics were investigated in detail by x-ray diffraction, scanning electron microscopy and cathodoluminescence. The Li‐Er-codoped ZnO films show a higher intensity of blue and red emissions than the Er-monodoped ZnO films. The behaviour of that enhancement is attributed to the modification of the local symmetry of the Er 3+ ion, which increases the intra 4f transition of the Er 3+ ion. The blue and red emissions have an important effect to improve the capacity of data storage.

The effects of sprayed lithium and erbium Co-doped ZnO thin films on the structural and cathodoluminescent properties

Summary form only given. Lithium and Erbium co-doped Zinc oxide thin films have been successfully deposited on heated glass substrates using spray pyrolysis technique. This study is an investigation of the Li effect on the enhancement of Cathodoluminescent (CL) intensity on the Er-monodoped. Crystallinity, morphology and luminescence characteristics were investigated in detail, by X-Ray Diffraction (XRD); Scanning Electron Microscopy (SEM) and Cathodoluminescent (CL). The Li-Er co-doped ZnO films show higher intensity of blue and red emissions than the Er monodoped ZnO films. The behaviour of that enhancement is attributed to the modification of the local symmetry of the Er3+ ion, which increases the intra 4f transition of Er3+ ion. Li+ ions also can reduce the OH groups in specimen, which is the other reason for enhancing the visible intensities. The blue and red emissions have an important effect to improve the capacity of data storage.