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A Polymerizationa??Assisted Grain Growth Strategy for Efficient and Stable Perovskite Solar Cells
摘要： Intrinsically, detrimental defects accumulating at the surface and grain boundaries limit both the performance and stability of perovskite solar cells. Small molecules and bulkier polymers with functional groups are utilized to passivate these ionic defects but usually suffer from volatility and precipitation issues, respectively. Here, starting from the addition of small monomers in the PbI2 precursor, a polymerization-assisted grain growth strategy is introduced in the sequential deposition method. With a polymerization process triggered during the PbI2 film annealing, the bulkier polymers formed will be adhered to the grain boundaries, retaining the previously established interactions with PbI2. After perovskite formation, the polymers anchored on the boundaries can effectively passivate undercoordinated lead ions and reduce the defect density. As a result, a champion power conversion efficiency (PCE) of 23.0% is obtained, together with a prolonged lifetime where 85.7% and 91.8% of the initial PCE remain after 504 h continuous illumination and 2208 h shelf storage, respectively.
关键词： polymerization,defect passivation,intermolecular exchanging grain growth,dimethyl itaconate,perovskite solar cells
更新于2025-09-19 17:13:59
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Secondary Grain Growth in Organica??Inorganic Perovskite Films with Ethylamine Hydrochloride Additives for Highly Efficient Solar Cells
摘要： The grain boundaries of perovskite polycrystalline are regarded as a defect region that not only provides carrier recombination sites but also introduces device degradation pathways. Efforts to enlarging the grain size of perovskite film and reducing its grain boundary are crucial for highly efficient and stable PSCs. Some effective methods that facilitate grain growth are post-deposition thermal annealing and solvent vapor annealing. However, a detailed understanding of grain growth mechanisms in perovskite films is lacking. In this study, perovskite films were prepared by adding ethylamine hydrochloride (EACl) to the precursor solution. This additive strategy promotes a new grain growth mode, secondary grain growth, in perovskite films. Secondary grain growth leads to much larger grains with high crystallographic orientation. These excellent properties lead to reduced grain boundaries and the densities of boundary defects. The improved film quality results in a prolonged charge–carrier lifetime and a significantly enhanced PCE. Compared with the PCE 18.42% of the control device, the PCE of the device with EACl additives reaches 21.07%.
关键词： Organic-inorganic perovskite,crystallographic orientation,grain growth,power conversion efficiency,solar cells
更新于2025-09-19 17:13:59
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Single-grain growth in Si film by chevron-shaped cw laser beam scanning
摘要： A single grain with a length of 450 μm and a width of 5–6 μm was grown in a 60 nm Si ?lm on SiO2 by scanning a chevron-shaped cw laser beam, which was formed by passing a linear laser beam through a novel one-sided Dove prism. The crystal did not have any dominant orientations in both the growth and normal directions. The orientation rotated about the transverse direction at a rate of 0.47–0.51°/μm in the forward direction, which suggests that the lattice constant at the ?lm surface was 0.049–0.053% larger than that at the ?lm bottom.
关键词： crystal orientation,one-sided Dove prism,single-grain growth,chevron-shaped cw laser beam,Si film
更新于2025-09-19 17:13:59
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3D grain growth simulation and experimental verification in laser beam melting of IN718
摘要： A predictive grain structure model originally used for selective electron beam melting (SEBM) is adapted to laser beam melting (LBM). Single lines with varying welding speeds were molten in a base plate made of polycrystalline IN718. The heat input is calculated with an analytical heat source model and the resulting melt pool geometry is compared with micrographs and high-speed camera shots. A typical welding microstructure is predicted by the grain growth model and confirmed with Electron Backscatter Diffraction (EBSD) measurements. With increasing line energies, a rising fragmentation of the grains is observed. This phenomenon is explained by an analyzation of the thermal gradients at the time of solidification of the grains.
关键词： additive manufacturing,laser beam melting,cellular automata,grain growth simulation
更新于2025-09-12 10:27:22
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Comprehensive analysis of blue diode laser-annealing of amorphous silicon films
摘要： The low temperature polycrystalline silicon (LTPS) method has proved to be a technical breakthrough, accomplishing semiconductor thin films with remarkable mobility for a range of high-performance displays, including liquid crystal display and organic light emitting diodes. However, utilizing a conventional excimer laser source for LTPS incurs high cost. In this paper, we demonstrate a comprehensive analysis of the crystallization mechanism of a-Si film (94 nm) and the thermal deformation of the glass substrate induced by Blue diode Laser Annealing (BLA). BLA provides high quality laterally grown crystals over 4 μm × 10 μm on glass substrates, which were examined by optical microscopy, scanning electron microscopy, and Raman spectroscopy. In addition, the permanent deformation introduced by the annealing process is numerically modeled, instantiating how to control the heat conduction from the thin film that affects the substrate. Our findings reveal that the permanent thermal deformation depth that can be obtained is comparable to the roughness of the silicon film for the optimum scanning speed and laser power. The combination of both experimental and numerical results elucidates the manifested physical mechanisms during the BLA process and provides the guidelines to improve the experimental parameters of this process.
关键词： Lateral grain growth,Glass deformation,Silicon thin film,Low Temperature Polycrystalline Silicon (LTPS),Blue diode laser
更新于2025-09-12 10:27:22
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δ‐CsPbI <sub/>3</sub> Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells
摘要： Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high-quality large-grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ-CsPbI3 intermediate phase growth (CsPbI3-IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI3)1–x(MAPbBr3)x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ-CsPbI3 intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase-assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.
关键词： CsPbI3 intermediate phase growth,stability,perovskite solar cells,sequential deposition,triple cation perovskite,grain growth
更新于2025-09-11 14:15:04
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Single Source Thermal Evaporation of Two-dimensional Perovskite Thin Films for Photovoltaic Applications
摘要： Hybrid two-dimensional (2D) halide perovskites has been widely studied due to its potential application for high performance perovskite solar cells. Understanding the relationship between microstructural and opto-electronic properties is very important for fabricating high-performance 2D perovskite solar cell. In this work, the effect of solvent annealing on grain growth was investigated to enhance the efficiency of photovoltaic devices with 2D perovskite films based on (BA)2(MA)3pb4i13 prepared by single-source thermal evaporation. Results show that solvent annealing with the introduction of solvent vapor can effectively enhance the crystallization of the (BA)2(MA)3pb4i13 thin films and produce denser, larger-crystal grains. The thin films also display a favorable band gap of 1.896 eV, which benefits for increasing the charge-diffusion lengths. The solvent-annealed (BA)2(MA)3pb4i13 thin-film solar cell prepared by single-source thermal evaporation shows an efficiency range of 2.54–4.67%. Thus, the proposed method can be used to prepare efficient large-area 2D perovskite solar cells.
关键词： solvent annealing,thermal evaporation,two-dimensional perovskite,photovoltaic applications,grain growth
更新于2025-09-11 14:15:04
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Grain growth in strontium titanate in electric fields: the impact of space-charge on the grain-boundary mobility
摘要： The present study investigates grain growth in the perovskite oxide strontium titanate in an electric field. The seeded polycrystal technique was chosen as it provides a sensitive and controlled setup to evaluate the impact of different parameters on grain growth due to the well-defined driving force for grain growth. Current blocking electrodes were used to prevent Joule heating. The results show faster grain growth, and thus, higher grain-boundary mobility at the negative electrode. It is argued that the electric field causes point-defect redistribution, resulting in a higher oxygen vacancy concentration at the negative electrode. The local oxygen vacancy concentration is suggested to affect the space-charge potential at the grain-boundaries. A thermodynamic treatment of the grain-boundary potential at a grain-boundary without field shows that for a high oxygen vacancy concentration less space-charge and less accumulation of cationic defects to the boundary occurs. Therefore, at the negative electrode, a higher oxygen vacancy concentration results in less space-charge and less accumulation of cationic defects. The lower degree of defect accumulation requires less diffusion of segregated defects during grain-boundary migration, so that at the negative electrode faster grain growth is expected, as found in the experiments.
关键词： field assisted,segregation,defects,space-charge,grain-boundaries,grain growth
更新于2025-09-10 09:29:36
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Highly-oriented (104) polycrystalline α-Al2O3 transparent ceramics prepared by a templated grain growth method
摘要： Highly-oriented (104) polycrystalline α-Al2O3 transparent ceramics were prepared by a templated grain growth (TGG) method using A-plane single-crystal sapphire as the template. This is the first report, to best of our knowledge, on polycrystalline α-Al2O3 ceramics oriented to non-optical axes. XRD and SEM results indicate that samples with high oriented grains and high-density structure are prepared. Compared to random samples, the oriented samples exhibited an increase in the real in-line transmittance (at 650 nm) from ~23% to ~62%. Moreover, the transmission remains a high level as the wavelength shifts toward the UV range (< 300 nm). This method can be extended to other uniaxial materials without optical axes in order to produce polycrystalline ceramics with excellent optical transparency.
关键词： polycrystalline α-Al2O3,oriented,transparent ceramics,grain growth
更新于2025-09-10 09:29:36
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Computational design of microstructures of textured ferroelectric ceramics by phase field simulation
摘要： Grain-oriented microstructure evolutions of ferroelectric ceramics were analyzed using phase field simulations. In templated grain growth, the coarsening behavior of the template particle was investigated in detail. Although a large grain boundary energy was set in the lateral direction along the casting plane, the template particle grew mainly in the vertical direction and gradually converted from a needle-like to rectangular grain. We demonstrated a critical interval of template particles for the preparation of highly textured ceramics. Therefore, different microstructures with high degrees of texture could be fabricated by adjusting and controlling the template size and fraction. Complementary experiments were guided by the computational design. Dense ferroelectric ceramics with high degrees of texture were obtained.
关键词： Templated grain growth,Ferroelectric ceramic,Textured ceramic,Computer simulation
更新于2025-09-10 09:29:36