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Novel Heteroleptic Ruthenium(II) Complexes with 2,2a?2- Bipyridines Containing a Series of Electron-Donor and Electron-Acceptor Substituents in 4,4a?2-Positions: Syntheses, Characterization, and Application as Sensitizers for ZnO Nanowire-Based Solar Cells
摘要： A novel series of complexes of the formula [Ru(4,4′-X2-bpy)2(Mebpy-CN)](PF6)2 (X = ?CH3, ?OCH3, ?N(CH3)2; Mebpy-CN = 4-methyl-2,2′-bipyridine-4′-carbonitrile) have been synthesized and characterized by spectroscopic, electrochemical, and photophysical techniques. Inclusion of the electron-withdrawing substituent ?CN at one bpy ligand and di?erent electron-donor groups ?X at the 4,4′-positions of the other two bpy ligands produce a ?ne tuning of physicochemical properties. Redox potentials, electronic absorption maxima, and emission maxima correlate well with Hammett’s σ p parameters of X. Quantum mechanical calculations are consistent with experimental data. All the complexes can be anchored through the nitrile moiety of Mebpy-CN over ZnO nanowires in dye-sensitized solar cells that exhibit an improvement of light to electrical energy conversion e?ciency as the electronic asymmetry increases in the series.
关键词： Electron-donor and Electron-acceptor substituents,Ruthenium(II) complexes,ZnO nanowire-based solar cells,Dye-sensitized solar cells,2,2′-Bipyridines
更新于2025-09-23 15:19:57
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Effect of working pressure on the properties of RF sputtered SnS thin films and photovoltaic performance of SnS-based solar cells
摘要： Tin sulfide (SnS) thin films were deposited with a single SnS target by radio frequency magnetron sputtering while varying the working pressure (0.6 Pa to 2.6 Pa), and the structural, chemical, electricelectrical and optical properties of the SnS thin films were investigated. X-ray diffraction results showed that all the SnS thin films had a (111) plane preferred growth orientation, and X-ray photoelectron spectroscopy verified that a SnS thin film was grown with an orthorhombic crystal structure, having the binding energy of 324.5 eV. Due to a long wavelength shift in the transmittance spectrum, the optical band gap decreased from 1.56 eV to 1.47 eV. A SnS-based conventional structure solar cell (Al/ITO/i-ZnO/CdS/SnS/Mo/SLG), prepared with a SnS absorption layer and deposited at a working pressure of 2.0 Pa, achieves the highest power conversion efficiency of 0.58%. It is confirmed that this result reveal to very high efficiency compared to other reports with conventional structure.
关键词： thin films,Tin sulfide,radio frequency magnetron sputtering,single target,SnS based solar cells,working pressure
更新于2025-09-19 17:13:59
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Highlights in Applied Mineralogy || 4. Microstructure analysis of chalcopyrite-type Cu2ZnSe4 and kesterite-type Cu2ZnSnSe4 absorber layers in thin film solar cells
摘要： Thin film solar cells equipped with polycrystalline compound semiconductors as functional layer for light absorption have continuously been improved in terms of solar energy conversion efficiency, such that they became a competitive alternative to well-established silicon-based solar cells. In 1905, Einstein published a comprehensive, physical description of the photoelectric effect [1] and thus provided the theoretical framework for upcoming research of photovoltaic technologies. The emergence of photovoltaic devices, however, only started about 50 years later, and for several decades, it persisted a niche technology mainly for aerospace applications. Among others, silicon (Si) was known to belong to the group of (extrinsic) elemental semiconductors, and due to its abundance, it was the very first absorber material to be used in solar cells. Triggered by the oil crisis in the 1970s, the research of solar energy conversion technologies finally got a tremendous stimulus. As a result, research not only of silicon-based solar cells but also of other absorber layer materials based on compound semiconductors have been much more extensively endeavored. The latter were also brought into focus in order to address some severe drawbacks of silicon-based solar cells. First of all, the high energy consumption in fabricating single crystal silicon results in a quite long energy amortization time. In addition, the requirements on crystallinity and purity are extremely high while a considerable amount of material is wasted upon slicing silicon wafers. Also, during the growth of silicon single crystals a certain concentration of dopants has to be incorporated in order to induce either extrinsic p-type or n-type conductivity. Despite the energy of the band gap of silicon fitting quite well with the optimal energy determined by the solar spectrum, silicon is an indirect semiconductor whose photonic electron transition from the valence band to the conduction band needs to be assisted by a phononic momentum transfer. This requirement of coincidence between a photon of appropriate energy being absorbed and a phonon transferring impulse to the electron leads to a reduced probability of events of photoelectric charge carrier generation. Correspondingly, the absorber thickness must be augmented in order to compensate the low absorption coefficient. These aforementioned issues, eventually, gave rise to reconsider photovoltaic technologies, being both economical and ecological reasonably applicable in a more widely spread manner. These demands have paved the way for thin film solar cell technologies using compound semiconductors. Those compound semiconductors are intrinsically conductive, and they possess a higher absorption coefficient due to direct electron band transitions (Fig. 4.1).
关键词： kesterite-type,chalcopyrite-type,absorber layer materials,light absorption,microstructure analysis,photovoltaic technologies,solar energy conversion efficiency,compound semiconductors,thin film solar cells,silicon-based solar cells
更新于2025-09-16 10:30:52
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CuSCN as Hole Transport Material with 3D/2D Perovskite Solar Cells
摘要： We report stable perovskite solar cells having 3D/2D perovskite absorber layers and CuSCN as an inorganic hole transporting material (HTM). Phenylethylammonium (PEA) and 4-fluoro-phenylethylammonium (FPEA) have been chosen as 2D cations, creating thin layers of (PEA)2PbI4 or (FPEA)2PbI4 on top of the 3D perovskite. The 2D perovskite as an interfacial layer, neutralizes defects at the surface of the 3D perovskite absorber and can protect from moisture-induced degradations. We demonstrate excellent charge extraction through the modified interfaces into the inorganic CuSCN HTM, with device efficiencies of above 18%, compared to 19.3% with conventional spiro-OMeTAD. Furthermore, we show significantly enhanced ambient stability.
关键词： Phenylethylammonium (PEA),CuSCN,hole transporting material (HTM),power conversion efficiencies (PCE),4-fluoro-phenylethylammonium (FPEA),perovskite based solar cells (PSCs)
更新于2025-09-12 10:27:22
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Mechanical Reliability of Photovoltaic Cells under Cyclic Thermal Loading
摘要： Metallic coatings placed on solar cell should retain their structural integrity over the life-span of the devices in order to ensure their reliable functioning. One critical component of such a life-assessment exercise is based on their response to the cyclic thermal stresses generated due to the temperature fluctuation, which is inevitable during regular operation of a solar cell and the difference in the thermal expansion coefficients of metal coatings and Si. Here, we have studied the impact of accelerated thermal cycling on the integrity of the semiconductor–metal layer in a commercial monocrystalline Si based photovoltaic solar cell comprising Ag finger-lining and Al backside coating. We observed that, compared to Si-Ag interface, the Al-Si interface was significantly weaker, wherein cracks easily nucleated and grew during thermal cycling between ?40°C and 90°C. The experimental results were augmented with finite element method (FEM), including extended-FEM (XFEM), simulations using geometry based on the actual microstructure of various metal-Si interfaces in the solar cell module. FEM-based simulations suggest excessive stress concentration at the interface of Al-Si eutectic-Al layers due to the irregular wavy nature of this interface. XFEM results indicate the critical role of the interfacial adhesion strength and roughness of the eutectic-Al interface on the crack growth and its propagation path. Based on the obtained results, a discussion on the fabrication of solar cell modules resistant to thermal stress induced structural damage is presented.
关键词： thermal cycling,metal-Si interface,Fracture,Si based solar cells,XFEM
更新于2025-09-12 10:27:22
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Simulating nanocrystal-based solar cells: A lead sulfide case study
摘要： Nanocrystal-based solar cells are promising candidates for next generation photovoltaic applications; however, the most recent improvements to the device chemistry and architecture have been mostly trial-and-error based advancements. Due to complex interdependencies among parameters, determining factors that limit overall solar cell efficiency are not trivial. Furthermore, many of the underlying chemical and physical parameters of nanocrystal-based solar cells have only recently been understood and quantified. Here, we show that this new understanding of interfaces, transport, and origin of trap states in nanocrystal-based semiconductors can be integrated into simulation tools, based on 1D drift-diffusion models. Using input parameters measured in independent experiments, we find excellent agreement between experimentally measured and simulated PbS nanocrystal solar cell behavior without having to fit any parameters. We then use this simulation to understand the impact of interfaces, charge carrier mobility, and trap-assisted recombination on nanocrystal performance. We find that careful engineering of the interface between the nanocrystals and the current collector is crucial for an optimal open-circuit voltage. We also show that in the regime of trap-state densities found in PbS nanocrystal solar cells (～1017 cm?3), device performance exhibits strong dependence on the trap state density, explaining the sensitivity of power conversion efficiency to small changes in nanocrystal synthesis and nanocrystal thin-film deposition that has been reported in the literature. Based on these findings, we propose a systematic approach to nanocrystal solar cell optimization. Our method for incorporating parameters into simulations presented and validated here can be adopted to speed up the understanding and development of all types of nanocrystal-based solar cells.
关键词： nanocrystal-based solar cells,simulation,charge carrier mobility,lead sulfide,drift-diffusion models,trap states
更新于2025-09-12 10:27:22