1,721,158 research outputs found
Mechanical Robustness Investigation of Organic Photovoltaics for Membrane Integrated Flexible Solar Cells
No full textFlexible Photovoltaics (PV) are promising alternatives to established crystalline silicon technologies for their possible integration onto flexible and translucent architectural membrane materials like Ethylene tetrafluoroethylene (ETFE) and Polytetrafluoroethylene (PTFE). This research proposes an experimental methodology based on coupled electrical characterization and uniaxial tensile tests to examine the mechanical robustness and the failure mechanism of a commercial organic photovoltaic module sample upon tensile loads
Thermoelectric characterization of flexible micro-thermoelectric generators
Full text linkA new experimental setup for the characterization of flexible micro-thermoelectric generators is reported. The system can measure the power generated and the thermoelectric conversion efficiency of devices under mechanical stresses and deformations, in atmospheric environment and under vacuum, in the temperature interval 293 K-423 K, as a function of the load resistance and of the mechanical pressure, with an uncertainty on the temperature difference of ±0.02 K. The system has been tested on commercial rigid devices and on a custom-made, flexible, proof-of-concept, organic-inorganic hybrid generator made of eight thermocouples. Repeatability on the power generated and conversion efficiency within 5% and 3%, respectively, was demonstrated, and accuracy of the measurement was granted by minimization of all the potential sources of heat flux losses
Development of Organic Field-effect Transistors for Operation at High Frequency
No full textTo date, the majority of the works in scientific literature have paid limited attention to the alternating current (AC) behavior of carbon-based field-effect transistors (FETs). This chapter reviews how it is possible to address the high-frequency operation of organic semiconductor-based FETs (OFETs). It introduces the transition frequency, a commonly adopted figure of merit for the characterization of the maximum operational frequency of a transistor. The chapter illustrates how the operational performance of an OFET depends on the physical and geometrical parameters of the device. It describes the requirements that the materials, geometry, and design of a device must satisfy for the improvement of the AC performance and their mutual interplay. The chapter also describes how the achievement of such requirements has been approached so far in the field of organic electronics, reporting the most significant works aimed at high-frequency operation of OFETs
Electronic transport regimes through an alkoxythiolated diphenyl-2,2′-bithiophene-based molecular junction diodes: Critical assessment of the thermal dependence
Full text linkThe detailed understanding of electronic transport through a single molecule or an ensemble of self-assembled molecules embedded between two metallic leads is still a matter of controversy. Multiple factors influence the charge transport in the molecular junction, with particular attention to be given to the band states of the electrodes, molecular orbital energies, bias potential and importantly molecule-electrode electronic coupling. Moreover it is not trivial to disentangle molecular contributions from other possible conduction pathways directly coupling the opposite electrodes. We here investigate the electronic transport properties of an ensemble molecular junction embedding an alkylthiol derivative of a diphenol substituted bithiophene (DPBT) by means of current vs. voltage and temperature dependent measurements. We explored different junction configurations using: micropores (Au//DPBT//Au and Au//DPBT-polymer conductor//Au) and conductive-atomic force microscopy (c-AFM). In all cases, we found a transition voltage VT of ∼0.35 V. The consistent presence of a similar VT in all the tested configurations is a strong, but not conclusive, indication of a molecular signature in the charge transport, which we assessed and confirmed by temperature dependent measurements. We found a transition from an incoherent resonant tunneling at low biases and close to room temperature, where transport is thermally activated with an activation energy of ∼85 meV, to a coherent tunneling at voltages higher than VT. Unlike many other molecular junctions reported in the literature, resonant conditions commonly attributed to a hopping transport regime can be found already at room temperature and very low biases for a molecule only ∼1.5 nm long. This paper is the first report to clearly show temperature activated transport through a short and not fully conjugated molecule. Moreover, we could clearly identify a regime at low temperatures and low bias where the transport mechanism is controlled by the thermal conductivity of the metal electrodes rather than the molecule. © The Royal Society of Chemistry 2015
Synthesis of polyaniline-based inks for inkjet printed devices: Electrical characterization highlighting the effect of primary and secondary doping
No full textEngineering applications for printed electronics demand solution processable electrically conductive materials, in the form of inks, to realize interconnections, piezoresistive pressure sensors, thermoresistive temperature sensors, and many other devices. Polyaniline is an intrinsically conductive polymer with modest electrical properties but clear advantages in terms of solubility and stability with temperature and in time. A comprehensive study, starting from its synthesis, primary doping, inkjet printing and secondary doping is presented, with the aim of elucidating the doping agent effects on its morphology, printability and electronic performanc
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