SiI4 Research Articles

Optimization of a novel lead-free MASiI3 based perovskite solar cell: A comprehensive study on device performance enhancement

Methylammonium Silicon Iodide (MASiI3), a novel perovskite material, has recently garnered significant attention for its potential to enhance the stability of solar cells. However, MASiI3-based perovskite solar cells (PSCs) have yet to achieve high performance. In this study, we utilized SCAPS-1D device modeling to investigate and optimize the performance of MASiI3-based PSCs, focusing on several key parameters. Our optimization efforts included the electron and hole transport layers (ETL and HTL), their respective thicknesses, doping densities (ND and NA), the TiO2/MASiI3 and MASiI3/Cu2O interface layers, series and shunt resistances, the metal back contact, and the influence of temperature. Through comparative analysis of various prospective materials, we identified TiO2 as the optimal ETL and Cu2O as the optimal HTL due to their superior band alignment. Our findings also highlighted the critical role of ambient temperature in maximizing power conversion efficiency (PCE). The proposed ETL and HTL materials demonstrated effective charge transport properties, contribute to enhanced device performance. Our optimized device achieved a Voc of 0.896 V, a Jsc of 42.47 mA/cm2, an FF of 76.94 %, and a remarkable PCE of 29.29 %. These results underscore the potential of MASiI3-based PSCs when utilizing TiO2 and Cu2O as charge-carrying materials and pave the way for further advancements in perovskite solar cell technology.

Theoretical study on low-lying states of silicon iodide:MRCI+Q calculation including spin-orbit coupling

High-level ab initio calculations are carried out to investigate the fine structure of electronic states correlating with the three lowest dissociation limits of the silicon iodide (SiI) molecule. The potential energy curves (PECs) of 23 Ʌ-S states and 45 Ω states are calculated by using multireference configuration interaction method with the Davidson correction (MRCI+Q). The spin-orbit coupling (SOC) effects are also accounted. Based on the calculated PECs, the spectroscopic constants of the bound states are evaluated, which are in a good agreement with previous experimental results. The predissociation mechanisms of the 22Δ state are studied, the perturbation on vibrational levels and predissociation channels are illuminated. Our investigation indicates that the higher vibrational levels (ν'≥ 7) of the doublet 12Σ+ are perturbed by the crossing quartet sate 14Σ−, which satisfactorily explains the perturbations of the (7,0) and (8,0) rovibronic band systems of the A-X transition detected in previous experiments. In addition, the transition dipole moments (TDMs), Franck-Condon factors (FCFs) and radiative lifetimes for spontaneous emission from the excited states to the ground state are evaluated.

Selective ALD of SiN using SiI4 and NH3: The effect of temperature, plasma treatment, and oxide underlayer

The initial growth of silicon nitride (SiN) thin films was studied during thermal atomic layer deposition (ALD) using silicon tetraiodide (SiI4) and ammonia (NH3) onto various oxide underlayers (native SiO2, sapphire, ALD Al2O3, and ALD ZrO2) at two deposition temperatures (200 and 350 °C). We found that the SiI4/NH3 process shows earlier nucleation on high-k oxide underlayers (sapphire, ALD Al2O3, and ALD ZrO2) compared with SiO2 at 200 °C. Interestingly, an NH3-plasma treatment reverses the selectivity between high-k oxides and SiO2: SiN growth has no nucleation delay on NH3-plasma-treated SiO2 but is severely delayed on NH3-plasma-treated high-k oxides at both temperatures (an incubation period of at least 300 cycles at 200 °C and 50 cycles at 350 °C).

Microclusters of Kinked Silicon Nanowires Synthesized by a Recyclable Iodide Process for High‐Performance Lithium‐Ion Battery Anodes

AbstractSilicon shows great promise as a high‐capacity anode material for lithium‐ion batteries. Nanostructuring silicon minimizes the impact of fracturing during charging and discharging. However, synthesizing nanostructured silicon typically requires complicated procedures with high manufacturing costs. Additionally, these complicated procedures typically have poor secondary particle formation, a requirement to achieve a high tap density. Here, a cost‐effective synthesis procedure which generates nearly ideal secondary particle clusters of nanostructured silicon is developed. The cost‐effectiveness is a result of the in operando generation of silicon iodide from iodine gas and low‐grade silicon microparticle. Decomposition of silicon iodide into crystalline silicon and iodine gas enables recycling of the iodine gas, allowing for near full reutilization of iodine in the following cycles. The optimal nanostructures and microstructures of silicon synthesized by the recyclable iodide decomposition reaction enables 83.6% capacity retention over 1000 cycles. The good performance is a result of well‐maintained morphology during cycling, enabling reutilization of the solid electrolyte interphase.

Silicon Tris(perchloro)dioxolene: A Neutral Triplet Diradical.

The reaction of ortho-quinones with silicon tetraiodide leads to neutral silicon trisdioxolenes in high yield, delivering the unknown oxidized form of triscatecholatosilicate dianions and the first example of open-shell semiquinonates connected via a single non-metal center. Silicon tris(perchloro)dioxolene is a stable diradical with a triplet ground state, as supported by X-ray diffraction; IR, resonance Raman, UV/Vis, and (VT)EPR spectroscopy; and Kohn-Sham broken-symmetry computations. Preliminary results suggest that the preferred magnetic ground state can be altered through variation of the substituents.

Equilibrium Deposition Rate of Silicon in Si-I2 and Si-H2-Cl2 Systems

The thermodynamic equilibrium deposition rates of silicon in Si-I2 and Si-H2-Cl2 systems were analyzed. These rates are discussed in terms of their applicability in industrial processes of Si purification. The behavior of silicon deposition for silicon tetraiodide (SiI4), silicon di-iodide and whole spectrum of Silicon-Hydrogen-Chlorine compounds were evaluated within a wide range of pressures and temperatures. A strong agreement between the theoretical model predictions and the experimental data was found for the SiI4 compound. Alternatives to the Herrick-Krieble's approximation for experimental SiI4 decomposition rates have been proposed for the actual operating pressures. The di-iodine technology has been analyzed in terms of its deficient SiI2 formation at 1200°C and the subsequent Si deposition and SiI4 formation at 800–900°C. An original approach was created to analyze the theoretical results for the Si-H2-Cl2 system using quasi-binary system coordinates: SiH4-SiCl4. The analysis of the results shows that the silicon deposition rate is independent of the temperature and the pressure. Such independence assumes that one, single mechanism governs the decomposition reaction for the (Si-H2-Cl2) system. It was concluded that a homogeneous nucleation is taking place for all Silicon-Hydrogen-Chlorine compounds within a temperature of 800–1400°C and a pressure of 1–100 atm.

The First Structurally Characterised Example of Silicon in an S6 Coordination Sphere

The reaction of sodium hydro‐tris(phenylthioimidazolyl)borate (NaTmPh) with silicon tetraiodide gives rise to the first crystallographically characterised molecular silicon compounds, [Si(TmPh)2] 2X (X = I– and I3–), in which the silicon is found in a regular S6 environment. The [Si(TmPh)2]2+ cation is subjected to analysis using DFT methods to explain why an S6 coordination motif is preferred to an S4 coordination motif.

Rapid Solid-State Synthesis of Nanostructured Silicon

Nanostructured silicon has recently been identified as an attractive material for a wide variety of uses from energy conversion and storage to biological applications. Here we present a new, rapid method of producing high-purity, nanostructured, unfunctionalized silicon via solid-state metathesis (SSM) in a matter of seconds. The silicon forms in a double displacement reaction between silicon tetraiodide and an alkaline earth silicide precursor. The products are characterized using powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Depending on the silicide precursor used, two different morphologies are obtained, either nanoparticles or dendritic nanowires. The variations in the morphologies are attributed to differences in the kinetics of the reactions.

Molecular Structure of Silicon Tetraiodide

The molecular geometry of silicon tetraiodide was determined by gas-phase electron diffraction at 378 K. The molecule has a regular tetrahedral shape with an Si—I bond length (r g) of 2.432(5) A and an I⋅⋅⋅I nonbonded distance (r g) of 3.971(8) A. There is an apparent anharmonicity in both the stretching and the bending vibrations, with the latter especially pronounced.

Selective area chemical beam epitaxial regrowth of Si-doped GaAs by using silicon tetraiodide for field effect transistor application

Selective area regrowth of silicon-doped GaAs has been successfully achieved by chemical beam epitaxy (CBE) on dry etched trench structures. Abrupt doping-interface and excellent doping controllability have also been achieved by using a novel silicon dopant source of silicon tetraiodide (SiI4). Metal-semiconductor field effect transistor (MESFET) and heterostructure field effect transistor (HFET) fabricated in this way with Ni/AuGe/Au alloyed contact contact metals on the Si-doped GaAs regrown layer reveal contact resistances as low as 3 × 10− 7 Ω cm2 and perfect selectivity there being no polycrystalline growth on the dielectric mask film.

Hexaiododisilane

The title compound, Si2I6, was prepared by reaction of silicon tetraiodide with finely divided metallic silver and subsequently purified by sublimation. The crystal structure can be regarded as an approximately dense packing of I atoms with the sequence ABAC with Si-Si dumb-bells occupying 1/6 of the octahedral sites. In an alternative description the structure is constituted of hexaiododisilane molecules with staggered conformation forming isolated slightly distorted octahedra with Si-Si dumb-bells in its centres.

Chemical beam epitaxial growth of Si-doped GaAs and InP by using silicon tetraiodide

Silicon tetraiodide (SiI4), which has a very weak Si–I bond strength (70 kcal/mol), is successfully employed as a novel Si dopant in the chemical beam epitaxy of GaAs and InP. No precracking is necessary before supplying SiI4 with He carrier gas. High electrical quality is ascertained for both GaAs and InP with linear Si doping controllability in the range from 2×1016 to 6×1018 cm−3 with a uniformity of less than 2% within a 3-in.-diam area. The electron mobility in a GaAs with a carrier concentration of 1×1017 cm−3 is 4400 cm2/V s and that in InP with a carrier concentration of 4×1017 cm−3 is 2400 cm2/V s, respectively. Abrupt interfaces and precise on-off controllability without any memory effect is also confirmed by secondary-ion-mass, spectroscopy measurements. The electrical activation ratio of Si in SiI4 for both GaAs and InP is almost 100% in the range studied here. These versatile features suggest that SiI4 is a promising candidate as a Si dopant source for chemical beam epitaxy growth.

Reactions of strontium, lanthanum, and europium iodides. Direct preparation of phosphorus triiodide from phosphates

Phosphorus triiodide has been prepared in high yields by the high-temperature reaction of metal iodide, metal phosphate, and silicon dioxide. Mixtures with europium, lanthanum, and strontium as the metallic element react under vacuum a t 800-1000 OC to produce large quantities of hexagonal (a = 7.133 (2), c = 7.414 (2) A) phosphorus triiodide and smaller quantities of diphosphorus tetraiodide and a polymorphic form of phosphorus. Products of the europium system have been characterized and include europium(I1) silicate, EuSi03, and europium(I1) tetraeuropium(II1) oxide trisilicate, EusO(Si04)3. Europium(I1) diiodide, EuI2, europium(I1) diiodide hydrate, EuIpH20, and silicon tetraiodide have also been identified as side products. X-ray data are reported for the products and the mass spectrum of PI3 has been obtained. The preparative reactions are presented, and thermodynamic calculations for the processes are described.

Protactinium(V) iodides

Protactinium pentaiodide, Pal5, is best prepared by direct union of the elements at 400–450° in a vacuum, but, if protactinium is not available, the pentaiodide is obtained in good yield by the reaction of silicon tetraiodide with protactinium pentachloride, pentabromide (both at 150–200°), or pentoxide (600°). Protactinium oxyiodides, PaOl3 and PaO2l, are obtained by reaction of the pentaiodide with antimony trioxide at 150°in vacuo or, less satisfactorily, by the action of oxygen on the pentaiodide. The oxytri-iodide disproportionates above 450° in a vacuum to yield the volatile pentaiodide and a residue of the dioxymonoiodide. The mixed bromo-iodide PaBr3l2 is obtained when the component pentahalides react together at 350°. Some chemical properties, X-ray powder diffraction results, and infrared spectra are reported for these compounds and for the hexaiodoprotactinate(V), Ph3MeAsPal6, which is formed by reaction of the component halides in non-aqueous solvents. Further infrared studies are also reported for the protactinium(V) oxybromides.

Molar Heat Capacity and Heat of Fusion of Silicon Tetraiodide

Molar Heat Capacity and Heat of Fusion of Silicon Tetraiodide

四ヨウ化ケイ素の熱容量および融解熱

四ヨウ化ケイ素の熱容量および融解熱

四ヨウ化シリコンの水素還元の製造実験とその性状

四ヨウ化シリコンの水素還元の製造実験とその性状

四ヨウ化シリコンの製造について

四ヨウ化シリコンの製造について

Silicon Tetraiodide. Freezing Point and Solubility in Common Organic Solvents.

Silicon Tetraiodide. Freezing Point and Solubility in Common Organic Solvents.

Impurity Introduction during Epitaxial Growth of Silicon

In this note it has been shown that the silicon iodide disproportionation process for growing epitaxial layers of silicon is also capable of transporting and codepositing desired impurities. Certain Group I11 and V elements such as B, P, As and Sb, can be introduced controllably into epitaxial layers of silicon during the growth. Impurity concentrations obtained cover 4 orders of magnitude, reaching far into the degenerate region. Therefore the process as described by Wajda et a1 is a new tool for the fabrication of various silicon semiconductor structures.