Résumé: Structural and electronic properties of doped oligothiophenes in the presence of p-toluenesulfonate acids A Chaalane, D Mahi, A Dkhissi Abstract : We investigate the geometric and electronic structure of singly oxidized oligothiophenes in the presence of the counterion named p-toluenesulfonate acid (p-TSA) by performing ab initio density functional theory calculations using Becke-Half-and-Half-Lee-Yang-and-Parr hybrid functional on chains of up to 12 thiophene rings. Different possibilities of positioning the counterion along the conjugated chain are studied. The calculations indicate that the side orientation is the most stable structure of pTh/p-TSA complex. Further, the influence of the counterion on the charge distribution and structural geometry of charged oligothiophenes is also investigated. In the last part of the work, the solid-state packing effects are considered by studying the stacking of two conjugated chains in the presence of two counterions. Our results are consistent with several experimental observations on similar conjugated polymers. Keywords Conducting polymers; Polaron; Doping; DFT; Ab initio calculations.

Résumé: ABSTRACT: A MEMS-based solid propellant microthruster array for space and military applications. A. Chaalane, R. Chemam, M. Houabes, R. Yahiaoui, A. Metatla, B.Ouari, N . Metatla, D. Mahi, A. Dkhissi, D. Esteve Combustion is an easy way to achieve large quantities of energy from a small volume, we developed a MEMS based solid propellant microthruster array for small spacecraft and micro-air-vehicle applications. A thruster is composed of a fuel chamber layer, a top-side igniter with a micromachined nozzle in the same silicon layer. Layers are assembled by adhesive bonding to give final MEMS array. The thrust force is generated by the combustion of propellant stored in a few millimeter cube chamber. The micro-igniter is a polysilicon resistor deposited on a low stress SiO2/SiNx thin membrane to ensure a good heat transfer to the propellant and thus a low electric power consumption. A large range of thrust force is obtained simply by varying chamber and nozzle geometry parameters in one step of Deep Reactive Ion Etching (DRIE). Experimental tests of ignition and combustion employing home made (DB+x%BP) propellant composed of a Double-Base and Black-Powder. A temperature of 250 °C, enough to propellant initiation, is reached for 40 mW of electric power. A combustion rate of about 3.4 mm/s is measured for DB+20%BP propellant and thrust ranges between 0.1 and 3,5 mN are obtained for BP ratio between 10% and 30% using a microthruster of 100 μm of throat wide.

Résumé: ABSTRACT: A combined theoretical and experimental investigation of the electronic structure and optical properties of poly(3-hexylthiophene) (P3HT), poly[3-(4-octylphenyl)thiophene] (POPT) and poly[3-(4-octylphenoxy)thiophene] (POPOT) is reported. In comparison with P3HT, POPT and POPOT exhibit better stabilities and the presence of an oxygen atom and/or a phenyl ring in the side chains enhances conjugation. Quantum chemical calculations have been performed on oligomers of increasing chain length to establish the changes in the electronic and optical properties when going from P3HT to the new derivative POPOT. The knowledge of the structure of these polymers is of utmost importance in understanding their optical properties in different phases (solution and condensed phase). The calculations indicate that, in opposition to P3HT and POPT polymers where the introduction of alkyl chains and the pendant phenyl disturbs the planarity of the backbone of the conjugated segment, POPOT has a better degree of organization in both states: the conjugated chain remains planar even in the presence of the phenoxy groups. Finally, the exciton binding energy is evaluated for these polymers and allows us to conclude that the POPOT is a promising polymer for photovoltaic applications when compared to P3HT and POPT. DOI: 10.1039/c2cp40170c

Résumé: Abstract : A new planar structure of solid propellant micro-rocket for micro-spacecraft and micro-air-vehicle applications is reported in this paper. We have successfully fabricated an array of micro-rockets using MEMS technology. For a low-power consumption, the micro-igniter used here is a resistor deposited on a low tensile stress thin membrane to ensure a good heat transfer to the propellant. Experimental tests of ignition and microcombustion employing double-base (DB) solid propellant mixed with black-powder (BP) are reported and discussed. Tests have showed successful and continuum combustion of about 1.3 mm diameter during few 100 ms from BP ratio in the mixture (x) of 10%. Thrust force delivered by considered structure dimensions, is ranging from 0.1 to 1 mN for x = 10%, 20% and 30%. We expect that this planar structure will deliver a suitable thrust force of few 10 mN when reducing micro-nozzle throat dimensions. Keywords : Micro-rocket; Micro-propulsion; Micro-igniter; PyroMEMS; Solid propellant; Double-base propellant; Black-powder. doi:10.1016/j.sna.2007.04.029

Résumé: Abstract : Within an European project,1 MEMS-based pyrotechnical devices have been developed. The operational concept is simply based on the combustion of a solid energetic material stored in a micromachined chamber. One possible application is the micropropulsion for nanosatellite but other applications can be addressed as microrocket for military needs. Arrays built to validate the concept contain 16 Ø1.5 mm × 1.5 mm rockets on 200 mm2. After a brief overview of the design and dimension, this paper presents the final experimentations that permitted to validate the pyrotechnical thrusters concept. At the millimetre scale, having a successful and reproducible ignition as well as a sustained propellant's combustion is a critical point of this technology. That is why, ignition, combustion and thrust has been experimented with great attention to fully validate the concept and results are reported in this paper. Keywords : Microthrusters; Pyrotechnical material; Ignition; Combustion; Thrust measurement doi:10.1016/j.sna.2005.03.017

Résumé: ABSTRACT: A MEMS-BASED SOLID PROPELLANT µTHRUSTER ARRAY FOR SPACE AND MILITARY APPLICATIONS A. Chaalane R. Chemam, M. Houabes, R. Yahiaoui, E. Algré, B. Ouari, N. Métatla, D. Mahi, D. Estève

Résumé: DFT Study of the Next Generation of Organic Solar Cells (OSC): A Comparison of HF and MP2 Methods with Experimental Data. A. Chaalane1-2, D. Mahi3, N. Métatla4, B. Ouari5, A. Dkhissi6 1LPR, University of Badji-Mokhtar-Annaba, Algeria, 2FEMTO-ST, Besançon, France, 3LGE, University of Amar-Telidgi-Laghouat, Algeria, 4University of Mila, Algeria, 5University of Tlemcen, Algeria, 6LAAS-CNRS, Toulouse, France ABSTRACT: Recently, Conjugated Polymers with excellent optical and electronic properties have been widely studied in the fields of polymers light-emitting diodes, thin film transistors, and polymers solar cells (PSCs). Particularly, PSCs have attracted much more attention because of their potential for low cost, light weights, and flexible large area devices. One of the most successful organic excitonic solar cells ois based on a polymer–fullerene blend. The control of electronic and optical properties of the polymer itself is thus of great interest in optimizing device efficiency. So in order to support, or even guide, the synthesis of novel materials with enhanced properties, quantum mechanical calculations are increasingly applied, in particular for the prediction of the optical properties of p-conjugated polymers. The optical band gap is a key parameter that controls, for instance, the efficiency of light absorption in solar cells. Therefore it is very important to theoretically study the optical and electronic properties of different oligothiophenes and polythiophenes with a view to designing tailor-made, processable materials. In this sprit, and as a test for the applicability of density functional theory (DFT) to conjugated polymers, various exchange correlation functionals have been used to calculate the equilibrium structure, the harmonic frequencies and optical properties of different oligothiophenes. Further several basis sets are used in order to determine the importance of the diffuse and polarization functions. Our analysis demonstrates that the 6-31+G* basis set is sufficient to reliably predict most properties of conjugated polymers, and the hybrid DFT functionals seem very promising for studying larger oligothiophenes systems where the MP2 method cannot be applied due to the a prohibitive computational cost. KEY WORDS: Conjugated polymers, Organic Solar Cells (OSC), oligothiophenes, DFT, quantum mechanics calculation, HF, MP2, hybrid functional.

Résumé: MEMS based Polysilicon Piezoresistor: Heater and Temperature Sensor Amar CHAALANE1,2,4, Réda YAHIAOUI2, Bachir OUARI3, Djillali MAHI4, Daniel ESTEVE5. 1LPR lab., Dept. of Physics, University of Annaba (Algeria) 2FEMTO-ST, Besançon (France) 3Dept. of Physics, University of Tlemcen (Algeria) 4Dept. of Electrotechnic, University of Laghouat (Algeria) 5LAAS/CNRS, Toulouse (France) Abstract: --------- In this work, we report the development of "on-chip" polycrystalline silicon (polysilicon) piezoresistor for heating and for temperature sensing. The design, fabrication and characterization of a demonstrator structure are presented. Such device can be used in many Micro-Electro-Mechanical- Systems (MEMS) applications, either as heater in ink jet, print heads, actuators, Bio-MEMS, chemical detectors and gas flow sensors, or as a resistors in temperature sensors, pressure sensors, accelerometers and light sensors [1]. The sensor is mainly composed of resistor patterned onto a thin bi-layers of SiO2 and SiNx membrane (Figure 1). Since the temperature control process is crucial to the development of heater, finite-element based electro-thermal simulation using COMSOL Multiphysics is performed to predict and optimize the heat transfer process. To evaluate the device performances, Infra-Red camera is used to photography the temperature profile of the 450 μm × 450 μm heating area (Figure 2). Furthermore, we measured a maximum temperature of 521°C employing only 73 mW of electric power supply. A test structure is used to determine the temperature variation of resistivity in doped polysilicon. A temperatures ranging from 25°C to 200°C are measured with a good sensitivity and low response time thanks to the concept of resistor on thin film membrane [2]. References: ----------- [1] A. A. Barlian, W.-T. Park, J. R. Mallon, A. Rastegar, and B. L. Pruitt, “Review: Semiconductor Piezoresistance for Microsystems”, Proceedings of the IEEE, vol. 97, n° 3, mars 2009. [2] A. Chaalane, C. Rossi, and D. Estève, “The formulation and testing of new solid propellant mixture (DB + x%BP) for a new MEMS-based microthruster", Sens. Actuators Phys., vol. 138, no. 1, pp. 161–166, 2007. Figure 1 : Schematic view of a MEMS base polysilicon resistor Figure 2 : Photo of a realized heater and temperature sensor

Résumé: Design, fabrication and characterization of a Polysilicon Micro-Heater on thin membrane for MEMS applications. Amar CHAALANE1, Djillali MAHI2, Bachir OUARI3, Daniel ESTEVE4, 1UBMA, Physics department, BP.12, Sidi-Ammar, 23000-Annaba (Algeria) 2UATL, Electrotechnic department, 03000-Laghouat (Algeria) 3University of Tlemcen (Algeria) 4LAAS-CNRS, 7 ave du colonel Roche, 31077-Toulouse (France) ABSTRACT: Micro-Heaters have been the subject of great interest due to their extensive applications in gas sensors, humidity sensors, pyrotechnical actuators and many other MEMS. A Micro-Heater should have a high sensitivity, low response time and low electrical power consumption. Hence his proper design is of critical importance. We designed a Polysilicon resistor patterned onto a very thin SiO2/SiNx low stressed membrane (see Figure 1). Since the temperature control process is crucial to the development of micro-heater, finite-element based electro-thermal modeling is performed to predict and optimize the heat transfer process. We have looked for geometric optimization of the structure to achieve optimizing temperature by performing simulation using COMSOL Multiphysics. In this work, we report the fabrication process and the characterization of Micro-Heater. The difference in property between thin film Ti/Au and Cr/Au for electrical contact layer are highlighted. A custom-built interface circuitry is used to electrically supply the resistor. In order to obtain the temperature profile for the 450μm×450μm heating area, Infra-Red camera is employed (see Figure 2). A maximum temperature of 520,8°C is observed for only 73,36mW of power supply. Figure 1: Image of the realized Polysilicon Micro-Heater on membrane Figure 2: IR image of a functioning Micro-Heater

Résumé: Optoelectronic and Excitonic Properties of Substituted oligothiophenes: toward designing novels materials for solar cells. A. Chaalane1, D. Mahi2, A. Dkhissi3-4 1LSC, UBM-Annaba, Algeria, 2LGE, UAT-Laghouat, Algeria 3LCT, Ghent University, Belgium, 4LAAS-CNRS, Toulouse, France ABSTRACT: In the last two decades, organic electronics has emerged as a vibrant field of research. On the applied research side, while not destined to replace silicon-based technologies,
-conjugated materials promise the advent of fully flexible devices for large-area displays, solid-state lighting, radio frequency identification tags, or solar cells; major chemical companies worldwide, such as Sumitomo, DuPont, Solvay, BASF, Ciba, and Merck to name but a few, are now involved in developing efficient sources of chemicals for organic electronics applications. In this paper we are interested to the solar cells: first principles Density Functional Theory (DFT) is employed to calculate the optoelectronic and excitonic properties of substituted oligothiophenes. We find that the range separated functional (LC-BLYP) significantly improves the poor description given by hybrid functionals. Among the polymers studied here, we determine the “promise” polymers for photovoltaic applications.

Résumé: Microsystème de Propulsion a Propergol Solide Intégré sur Silicium A. Chaalane1, D. Mahi2, C. Rossi3, D.Estève3 1 Département de Physique, UBM-Annaba, 23000 Annaba 2 Laboratoire d’étude et développement de matériaux diélectriques et semi conducteurs -Université Ammar Tlidji - Laghouat 3 LAAS-CNRS, 7 av. du colonel Roche, 31077 Toulouse cedex 4 (France) Résumé : La miniaturisation des modules de propulsion dans le but de satisfaire aux besoins des micro/nano-satellites (<20kg) est un point crucial pour réaliser le maintien à poste et les manœuvres orbitales (désorbitation, …etc). Les niveaux de poussée (de quelques µN à quelques mN) ainsi que la précision requise ne peuvent pas être atteints avec les propulseurs conventionnels, volumineux, lourds et coûteux. Avec le développement des technologies MEMS (Micro-ElectroMechanical System), la réalisation de microsystèmes de propulsion est possible. Dans ce papier, nous présentons un travail portant sur les micro-propulseurs sur silicium. Un prototype de microsystème de propulsion à propergol solide a été conçu, réalisé et testé avec succès afin d’envisager son utilisation dans le domaine spatial. Mots clés : micro-propulseur, actionneur pyrotechnique, MEMS, micro initiateur silicium, membrane diélectrique, micro usinage du silicium.

Résumé: ABSTRACT: A new planar structure of solid propellant micro-rocket for micro-spacecraft and Micro-Air-Vehicle applications is reported in this paper. We have successfully fabricated an array of micro-rockets using MEMS technology. For a low-power consumption, the micro-igniter used here is a resistor deposited on a low tensile stress thin embrane to ensure a good heat transfer to the propellant. Experimental tests of ignition and microcombustion employing Double-Base (DB) solid propellant mixed with Black-Powder (BP) are reported and discussed. Tests have showed successful and continuum combustion of about 1.3mm diameter during few 100ms from BP ratio in the mixture (x) of 10%. Thrust force delivered by considered structure dimensions, is ranging from 0.1mN to 1mN for x=10%, 20% and 30%. We expect that this planar structure will deliver a suitable thrust force of few 10mN when reducing micro-nozzle throat dimensions. Keywords: micro-propulsion, micro-rocket, solid propellant, Double-Base propellant, Black-Powder, micro-igniter, pyroMEMS.

Résumé: ABSTRACT: Solid propellant micro-thruster is an alternative option to cold gas and field emission electric propulsion systems for space. It can also be used for autonomous Micro-Air-Vehicles (MAV) micro-propulsion in complement to electrical motor. It is simple, cheap and requires low power to ignite the micro-combustion of a few milli-grammes of a solid propellant. This paper presents two concepts of solid propellant micro-thruster. The first one is a sandwich of three parts: a combustion chamber (with one or several wafers), an igniter and a convergent-divergent nozzle. They produce force thrust between 0.28mN and 14mN making them good candidates for station keeping or orbit maneuvers for micro-spacecraft. The second one is a planar structure, more powerful in comparison with the first structure. It is designed to deliver thrusts between 10mN and 50mN for civil and military applications, like the stabilization of MAV during tationary fly. It is made of three layers : (i) a combustion chamber and a micro -nozzle are micromachined on the same silicon wafer;(ii) a ceramic reservoir is reported on the top;(iii) a Pyrex glass seals the back side of the structure. The design, the micro-fabrication and the characterization of both structures are reported.