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Side chain dynamics in semiconducting polymer MEH‐PPV
摘要： The characteristic nanoscale dynamics of the alkyl side groups in the light-emitting polymer poly[2-methoxy-5-(20-ethyl-hexyloxy)-1,4-phenylene vinylene] have been investigated using quasi-elastic neutron scattering (QENS). The measurements were taken below the polymer’s glass transition (T ≤ Tg ’ 353 K), where the main backbone is in a rigid state and does not contribute to the broadening of the QENS signal. An analytical diffusion model consisting of a static term and two dynamical components, characterizing the flexible side groups, provide an excellent fit to the experimental data. The two observed dynamical processes are all localized in character, with no meaningful dependence on temperature. The faster process, with characteristic timescale of (cid:2)18 ps at room temperature (RT), can be linked to the average mobility of the terminal protons of the alkyl chain, while the slower process, with characteristic timescale of (cid:2)170 ps at RT, to those protons at the other end of the alkyl chain, closest to the backbone. While the fraction of mobile protons contributing to the QENS signal increases with increasing temperature, the characteristic timescale and confining volume within which the protons are able to move locally depend chiefly on the polymer conformational state. ? 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47394.
关键词： quasi-elastic neutron scattering,semi-conducting polymer,optical and photovoltaic applications,polymer dynamics,spectroscopy
更新于2025-09-23 15:22:29
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Mixed-Cation Mixed-Metal Halide Perovskites for Photovoltaic Applications: A Theoretical Study
摘要： Perovskite solar cells based on multiple cations have shown excellent optoelectronic properties with high power conversion efficiency. Herein, the structural, electronic, and optical properties of mixed-cation mixed-metal perovskites MA1?xCsxPb0.25Sn0.75I3 were studied by employing the first-principles calculations for the first time. Our calculated results reveal that these perovskite materials possess direct band gaps in the range of 1.0?1.3 eV. Moreover, these compounds show excellent photovoltaic performance in terms of strong optical absorption coefficients compared with MAPbI3. Particularly, they also exhibit good structural stability and decrement of lead content. These results demonstrated that mixed-cation mixed-metal perovskites may be potential candidates for high-efficiency light-absorbing materials.
关键词： mixed-cation mixed-metal perovskites,electronic properties,optical properties,first-principles calculations,photovoltaic applications,structural stability
更新于2025-09-23 15:21:01
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Formation of stable 2D methylammonium antimony iodide phase for lead-free perovskite-like solar cells
摘要： The presence of lead in novel hybrid perovskite-based solar cells remains a significant issue regarding commercial applications. Therefore, antimony-based perovskite-like A3M2X9 structures are promising new candidates for low toxicity photovoltaic applications. So far, MA3Sb2I9 was reported to only crystallize in the ‘zero-dimensional’ (0D) dimer structure with wide indirect bandgap properties. However, the formation of the 2D layered polymorph is more suitable for solar cell applications due to its expected direct and narrow bandgap. Here, we demonstrate the first synthesis of phase pure 2D layered MA3Sb2I9, based on antimony acetate dissolved in alcoholic solvents. Using in situ XRD methods, we confirm the stability of the layered phase towards high temperature, but the exposure to 75 % relative humidity for several hours leads to a rearrangement of the phase with partial formation of the 0D structure. We investigated the electronic band structure and confirmed experimentally the presence of a semi-direct bandgap at around 2.1 eV. Our work shows that careful control of nucleation via processing conditions can provide access to promising perovskite-like phases for photovoltaic applications.
关键词： antimony,perovskite solar cells,2D materials,lead-free,photovoltaic applications
更新于2025-09-23 15:21:01
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Effect of film thickness and evaporation rate on co-evaporated SnSe thin films for photovoltaic applications
摘要： SnSe thin films were deposited by a co-evaporation method with different film thicknesses and evaporation rates. A device with a structure of soda-lime glass/Mo/SnSe/CdS/i-ZnO/ITO/Ni/Al was fabricated. Device efficiency was improved from 0.18% to 1.02% by a film thickness of 1.3 mm and evaporation rate of 2.5 ? s?1 via augmentation of short-circuit current density and open-circuit voltage. Properties (electrical, optical, structural) and scanning electron microscopy measurements were compared for samples. A SnSe thin-film solar cell prepared with a film thickness of 1.3 mm and evaporation rate of 2.5 ? s?1 had the highest electron mobility, better crystalline properties, and larger grain size compared with the other solar cells prepared. These data can be used to guide growth of high-quality SnSe thin films, and contribute to development of efficient SnSe thin-film solar cells using an evaporation-based method.
关键词： SnSe thin films,film thickness,co-evaporation,photovoltaic applications,evaporation rate
更新于2025-09-23 15:21:01
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One-step spray of Cu2NiSnS4 thin films as absorber materials for photovoltaic applications
摘要： A simple one-step ?Spray Pyrolysis? technique was developed for preparing Cu2NiSnS4 (CNTS) thin film followed by an annealing treatment process. Originally, the spray technique was successfully used to deposit the thin film onto glass substrate at 250 °C for 60 min spray duration. Again, the deposited thin film was annealed in a sulfur atmosphere at a temperature of 500 °C during 30 min. The sulfured thin film exhibits (111), (220) and (311) orientations correspond well to the cubic CNTS structure and other impurity compounds. The SEM data exhibit a uniform, rough and compact topography of CNTS thin films with an average-thickness of 1.36 μm. The absorption coefficient is found to be higher than 104 cm?1 in the visible region while the direct band energy of 1.62 eV, which is eminently suitable for use as an absorber in the solar cell. The complex impedance diagrams indicate the decrease of resistance by increasing temperature, which attributes to a semiconductor behavior. The close values of activation energies 0.63 and 0.54 eV determined from both angular frequency and DC conductivity indicate that the carrier transport mechanism is thermally activated.
关键词： Cu2NiSnS4,Photovoltaic applications,Spray Pyrolysis,Semiconductor behavior,Thin films
更新于2025-09-23 15:21:01
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Processing and Study of Optical and Electrical Properties of (Mg, Al) Co-Doped ZnO Thin Films Prepared by RF Magnetron Sputtering for Photovoltaic Application
摘要： In this study, high transparent thin films were prepared by radio frequency (RF) magnetron sputtering from a conventional solid state target based on ZnO:MgO:Al2O3 (10:2 wt %) material. The films were deposited on glass and silicon substrates at the different working pressures of 0.21, 0.61, 0.83 and 1 Pa, 300 °C and 250 W of power. X-ray diffraction patterns (XRD), atomic force microscopy (AFM), UV-vis absorption and Hall effect measurements were used to evaluate the structural, optical, morphological and electrical properties of thin films as a function of the working pressure. The optical properties of the films, such as the refractive index, the extinction coefficient and the band gap energy were systematically studied. The optical band gap of thin films was estimated from the calculated absorption coefficient. That parameter, ranged from 3.921 to 3.655 eV, was hardly influenced by the working pressure. On the other hand, the lowest resistivity of 8.8 × 10?2 ? cm was achieved by the sample deposited at the lowest working pressure of 0.21 Pa. This film exhibited the best optoelectronic properties. All these data revealed that the prepared thin layers would offer a good capability to be used in photovoltaic applications.
关键词： working pressure,Al doped ZnO-MgO powder,RF magnetron sputtering,photovoltaic applications,thin films,solid-state method,optoelectronic properties
更新于2025-09-23 15:21:01
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Six novel carbon and silicon allotropes with their potential application in photovoltaic field
摘要： By stacking up five novel cagelike structures, three novel three-dimensional (3D) sp3 bonding networks, named hP24, hP30 and hP36, were predicted in this work for the first time. These three newly discovered structures have trigonal unit cell with the space groups of P-3m1, P-3m1 and P3m1, respectively. Using first-principle calculations, the physical properties, including structural, mechanical, electronic and optical properties of C and Si in hP24, hP30 and hP36 phases were systematically studied. All these newly discovered carbon and silicon allotropes were proven to be thermodynamically and mechanically stable. The wide indirect bandgap value in range of 3.89 ~ 4.03 eV suggests that C in hP24, hP30 and hP36 phases have the potential to applied in high frequency and high power electronic devices. The direct bandgap value in range of 0.60 ~ 1.16 eV, the smaller electron and hole effective mass than diamond-Si, and the significantly better photon absorption characteristics than diamond-Si suggest that hP24-Si, hP30-Si and hP36-Si are likely to have better performance in photovoltaic applications than diamond-Si. hP24-Si also have the potential to be applied in infrared detectors.
关键词： carbon and silicon allotropes,effective mass,direct bandgap,photovoltaic applications,stability
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Wavelength-Conversion Material-Mediated Semiconductor Bonding for Photovoltaic Applications
摘要： Wavelength-conversion material-mediated semiconductor wafer bonding has been demonstrated, by utilizing an adhesive and viscous organic matrix embedding fluorescent particles. The wavelength-converting heterointerface can practically lead the spectral light incidence suitable for each photovoltaic material. This bonding and interfacial scheme is expected to enhance solar cell efficiency and structure flexibility by photon management and current matching among subcells. Moreover, our novel scheme provides the bonding formation and the interfacial function generation simultaneously, and therefore potentially realizes low-cost and high-throughput production processes.
关键词： fluorescent particles,wavelength-conversion,solar cell efficiency,photovoltaic applications,semiconductor bonding
更新于2025-09-23 15:19:57
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Nanoscale Interfaces of Janus Monolayers of Transition Metal Dichalcogenides for 2D Photovoltaic and Piezoelectric Applications
摘要： Using first-principles calculations, we demonstrate a combination of two emergent fields, type-II van der Waal heterostructures and Janus structures, for the purpose of optimizing the harvesting of solar and nanoelectromechanical energy. The most stable stacking order in these nanoscale heterobilayers comprising of Janus monolayers of transition metal dichalcogenides has been ascertained based on the interlayer binding energies. The binding energies in WSeTe/WSTe and MoSeTe/WSTe heterobilayers are found to be -27.93 and -25.67 meV/?2 at an equilibrium interlayer layer distance of 3.25 ? and 3.32 ? respectively, indicating the exothermicity in the process of heterobilayer formation and hence, its experimental feasibility. The mechanical and dynamical stabilities have also been confirmed for these heterobilayers using the Born Huang stability criteria and phonon dispersion calculations. Our results unveil the mechanism underlying the electronic, piezoelectric, photocatalytic properties and carrier mobility in these Janus heterobilayers. Power conversion efficiency in the 2D ultrathin excitonic solar cells constituted by some of the heterobilayers studied in this work, has been found to lie in the range of 15-20%. Moreover, a very high carrier mobility (>200 cm2/V.s) together with a large visible light absorption coefficient (α ~ 105 cm-1) has been observed in these hetero-bilayers. The piezoelectric coefficients in these ultrathin heterobilayers (d33 = 13.91 pm/V) is found to reach close to the values obtained in multilayer/bulk structures built from Janus monolayers of Mo-based dichalcogenides. Our findings highlight the promising applications of these heterobilayers in ultrathin excitonic solar cells, nanoelectronics and nanopiezotronics.
关键词： van der Waals heterostructures,transition metal dichalcogenides,photovoltaic applications,Janus monolayers,piezoelectricity,carrier mobility
更新于2025-09-23 15:19:57
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Multiple epitaxial lift-off of stacked GaAs solar cells for low-cost photovoltaic applications
摘要： This paper presents a multilayer peeling from a stacked cell structure as an approach for the cost reduction of III–V solar cells. We demonstrate the separation of two-layer stacked GaAs solar cells with Al(Ga)As release layers on the GaAs substrate into individual layers without cracks. The cells in each layer peeled from the stacked structure show equivalent device performances. Thermal cycling tests with repeated heating to 85 °C and cooling to ?40 °C show that the flexible GaAs thin-film cell exhibits a high durability against temperature changes. Further, a damp heat test conducted at 85 °C and 85% humidity indicates that the cell has long-term stability. These results suggest that the flexible GaAs thin-film cells fabricated by peeling from stacked structures have a high reliability and prove that the separation of the stacked cell structures into individual layers is effective in fabricating low-cost III–V solar cells.
关键词： epitaxial lift-off,cost reduction,damp heat test,photovoltaic applications,thermal cycling,GaAs solar cells
更新于2025-09-23 15:19:57