Nam, M., Park, Y., Lee, C., Kim, G., Larrain, F. A., Fuente-Hernandez, C., et al. (2023). Single-layer organic photovoltaics fabricated via solution-based electrical doping of ternary bulk heterojunction films. Chem. Eng. J., 466, 143340.
Abstract: The commercial viability of organic photovoltaics (OPVs) can be improved by simplifying their device geometry and easing fabrication complexity. Here, we demonstrate that solution-based p-type electrical doping of ternary bulk heterojunction (BHJ) films, which comprise 2 donor polymers and 1 fullerene acceptor (2D:1A), enables the realization of efficient single-layer OPVs. Systematic and detailed investigations of the optoelectronic charac-teristics of films with varying donor ratios, and their photovoltaic performance, demonstrate p-type electrical doping via post-process immersion into a 12-molybdophosphoric acid hydrate (PMA) solution, resulting in a reduced trap density and charge recombination without significantly changing the BHJ morphology. Further-more, PMA doping of films comprising optimized ternary blend compositions and polyethylenimine enables the demonstration of single-layer OPVs with economic top electrode metals and a high level of performance under outdoor and indoor illumination conditions. These PMA-doped 2D:1A BHJ films are an attractive platform to reduce the efficiency-cost gap and accelerate the commercialization of OPVs for emerging applications.
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Pabba, D. P., Rao, B. V. B., Thiam, A., Kumar, M. P., Mangalaraja, R. V., Udayabhaskar, R., et al. (2023). Flexible magnetoelectric PVDF-CoFe2O4 fiber films for self-powered energy harvesters. Ceram. Int., 49(19), 31096–31105.
Abstract: Integrating the concept of magnetoelectric in the mechanical energy harvesters through the magneto-mechanoelectrical (MME) nanogenerators has been explored to realize the self-powered devices. The magnetoelectric interaction enabled the output performance of the MME nanogenerator under magnetic stimulus of the active components of the energy harvesters. In this perspective, we fabricated a flexible biomechanical and MME nanogenerator using PVDF/CoFe2O4 fibers composite films. CoFe2O4 fibers were synthesized by the electrospinning technique and the process parameters were optimized to achieve uniform and bead-free fibers. The structural and morphological properties were investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The structural and morphology revealed the fibers calcined at 800 degrees C with a heating rate of 2 degrees C/min produced bead-free continuous fibers with a fiber diameter of 210 nm with cubic spinel crystalline structure with a crystallite size of 34 nm. These highly crystalline fibers were used to fabricate PVDF/CoFe2O4 fibers composite films. The magnetoelectric behaviour of the films verified through polarization vs. electric field (P-E) loops under magnetic field. The leakage current density and mechanism of the composite films were investigated, and it was discovered that the mechanism was due to Schottky emission. Further the energy harvesting performance of the composite films were estimated where the nanogenerator achieved an output voltage of 13 V under biomechanical tapping force while the MME nanogenerator produced 3.5 V under a low frequency stray magnetic field of 6 Oe with a power density of 28 & mu;W/m2.
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Pabba, D. P., Satthiyaraju, M., Ramasdoss, A., Sakthivel, P., Chidhambaram, N., Dhanabalan, S., et al. (2023). MXene-Based Nanocomposites for Piezoelectric and Triboelectric Energy Harvesting Applications. Micromachines, 14(6), 1273.
Abstract: Due to its superior advantages in terms of electronegativity, metallic conductivity, mechanical flexibility, customizable surface chemistry, etc., 2D MXenes for nanogenerators have demonstrated significant progress. In order to push scientific design strategies for the practical application of nanogenerators from the viewpoints of the basic aspect and recent advancements, this systematic review covers the most recent developments of MXenes for nanogenerators in its first section. In the second section, the importance of renewable energy and an introduction to nanogenerators, major classifications, and their working principles are discussed. At the end of this section, various materials used for energy harvesting and frequent combos of MXene with other active materials are described in detail together with the essential framework of nanogenerators. In the third, fourth, and fifth sections, the materials used for nanogenerators, MXene synthesis along with its properties, and MXene nanocomposites with polymeric materials are discussed in detail with the recent progress and challenges for their use in nanogenerator applications. In the sixth section, a thorough discussion of the design strategies and internal improvement mechanisms of MXenes and the composite materials for nanogenerators with 3D printing technologies are presented. Finally, we summarize the key points discussed throughout this review and discuss some thoughts on potential approaches for nanocomposite materials based on MXenes that could be used in nanogenerators for better performance.
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Varona, J., De Fazio, R., Velazquez, R., Giannoccaro, N. I., Carrasco, M., & Visconti, P. (2020). MEMS-based Micro-scale Wind Turbines as Energy Harvesters of the Convective Airflows in Microelectronic Circuits. Int. J. Renew. Energy. Res., 10(3), 1213–1225.
Abstract: As an alternative to conventional batteries and other energy scavenging techniques, this paper introduces the idea of using micro-turbines to extract energy from wind forces at the microscale level and to supply power to battery-less microsystems. Fundamental research efforts on the design, fabrication, and test of micro-turbines with blade lengths of just 160 μm are presented in this paper along with analytical models and preliminary experimental results. The proof-of-concept prototypes presented herein were fabricated using a standard polysilicon surface micro-machining silicon technology (PolyMUMPs) and could effectively transform the kinetic energy of the available wind into a torque that might drive an electric generator or directly power supply a micro-mechanical system. Since conventional batteries do not scale-down well to the microscale, wind micro-turbines have the potential for becoming a practical alternative power source for microsystems, as well as for extending the operating range of devices running on batteries.
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