Fabrication of CH₃NH₃PbI₃/PVP Composite Fibers via Electrospinning and Deposition.
Ontology highlight
ABSTRACT:
SUBMITTER: Chao LM
PROVIDER: S-EPMC5455475 | biostudies-other | 2015 Aug
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Hybrid organic-inorganic perovskite materials have attracted extensive attention due to their impressive performance in photovoltaic devices. One-dimensional perovskite CH₃NH₃PbI₃ nanomaterials, possessing unique structural features such as large surface-to-volume ratio, anisotropic geometry and quantum confinement, may have excellent optoelectronic properties, which could be utilized to fabricate high-performance photodetectors. However, in comparison to CH₃NH₃PbI₃ thin films, reports on the fabrication of CH₃NH₃PbI₃ nanowires for optoelectrical application are rather limited. Herein, a two-step spin-coating process has been utilized to fabricate pure-phase and single-crystalline CH₃NH₃PbI₃ nanowires on a substrate without mesoporous TiO₂ or Al₂O₃. The size and density of CH₃NH₃PbI₃ nanowires can be easily controlled by changing the PbI₂ precursor concentration. The as-prepared CH₃NH₃PbI₃ nanowires are utilized to fabricate photodetectors, which exhibit a fairly high switching ratio of ~600, a responsivity of 55 mA/W, and a normalized detectivity of 0.5 × 1011 jones under 532 nm light illumination (40 mW/cm²) at a very low bias voltage of 0.1 V. The as-prepared perovskite CH₃NH₃PbI₃ nanowires with excellent optoelectronic properties are regarded to be a potential candidate for high-performance photodetector application.
| S-EPMC5977332 | biostudies-literature
Project description:CH3NH3PbI(3-x)Cl(x) perovskites enable fabrication of highly efficient solar cells. Chloride ions benefit the morphology, carrier diffusion length, and stability of perovskite films; however, whether those benefits stem from the presence of Cl(-) in the precursor solution or from their incorporation in annealed films is debated. In this work, the photothermal-induced resonance, an in situ technique with nanoscale resolution, is leveraged to measure the bandgap of CH3NH3PbI(3-x)Cl(x) films obtained by a multicycle coating process that produces high efficiency (∼16%) solar cells. Because chloride ions modify the perovskite lattice, thereby widening the bandgap, measuring the bandgap locally yields the local chloride content. After a mild annealing (60 min, 60 °C) the films consist of Cl-rich (x < 0.3) and Cl-poor phases that upon further annealing (110 °C) evolve into a homogeneous Cl-poorer (x < 0.06) phase, suggesting that methylammonium-chrloride is progressively expelled from the film. Despite the small chloride content, CH3NH3PbI(3-x)Cl(x) films show better thermal stability up to 140 °C with respect CH3NH3PbI3 films fabricated with the same methodology.
| S-EPMC4746708 | biostudies-literature
Project description:Electrospinning (e-spinning) is an emerging technique to prepare ultrafine fibers. Polyphenylene sulfide (PPS) is a high-performance resin which does not dissolve in any solvent at room temperature. Commercial PPS fibers are produced mainly by meltblown or spunbonded process to give fibers ~20 μm in diameter. In this research, an in-house designed melt electrospinning device was used to fabricate ultrafine PPS fibers, and the e-spinning operation conducted under inert gas to keep PPS fibers from oxidizing. Under the optimum e-spinning conditions (3 mm of nozzle diameter, 30 kV of electrostatic voltage, and 9.5 cm of tip-to-collector distance), the as-spun fibers were less than 8.0 μm in diameter. After characterization, the resultant PPS fibers showed uniform diameter and structural stability. Compared with commercial PPS staple fibers, the obtained fibers had a cold crystallization peak and 10 times higher storage modulus, thereby offering better tensile tenacity and more than 400% elongation at break.
| S-EPMC6473442 | biostudies-literature
Project description:Cholesteryl ester liquid crystals exhibit thermochromic properties related to the existence of a twisted nematic phase. We formulate ternary mixtures of cholesteryl benzoate (CB), cholesteryl pelargonate (CP), and cholesteryl oleyl carbonate (COC) to achieve thermochromic behavior. We aim to achieve thermochromic fibers by incorporating the liquid crystal formulations into electrospun fibers. Two methods of incorporating the liquid crystal (LC) are compared: (1) blend electrospinning and (2) coaxial electrospinning using the same solvent system for the liquid crystal. For blend electrospinning, intermolecular interactions seem to be important in facilitating fiber formation since addition of LC can suppress bead formation. Coaxial electrospinning produces fibers with higher nominal fiber production rates (g/hr) and with higher nominal LC content in the fiber (wt. LC/wt. polymer assuming all of the solvent evaporates) but larger fiber size distributions as quantified by the coefficient of variation in fiber diameter than blend electrospinning with a single nozzle. Importantly, our proof-of-concept experiments demonstrate that coaxially electrospinning with LC and solvent in the core preserves the thermochromic properties of the LC so that thermochromic fibers are achieved.
| S-EPMC7240475 | biostudies-literature
Project description:Four solvents (isopropanol (IPA), n-butyl alcohol (NBA), n-amyl alcohol (NAA), and n-hexyl alcohol (NHA)) were investigated to prepare CH?NH?I (methylammonium iodide, MAI) solutions to transform PbI? film into CH?NH?PbI? (MAPbI?) film. It was found that the morphology of the perovskite MAPbI? film was not only affected by the chain of the solvent molecule, but also by the concentration of MAI. The use of solvents with a long alkyl chain (NAA and NHA) allowed the MAPbI? to grow via an in situ transformation step, which easily made the perovskite films compact, but with a high surface roughness due to the growth of unexpected nanorods/nanoplates. The solvent with a short alkyl chain (IPA) led to the dissolution-crystallization growth mechanism, resulting in rapid generation of perovskite films with a number of pinholes. A high-quality (compact, smooth, pinhole-free) perovskite film was obtained with NBA and an optimized MAI concentration of 8 mg/mL. The corresponding perovskite solar cells achieved a maximum power conversion efficiency (PCE) of 16.66% and average PCE of 14.76% (for 40 cells).
| S-EPMC6265889 | biostudies-other
Project description:In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS), polyvinylpyrrolidone (PVP) and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400-500 nm and wall thickness of 50-60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL) of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.
| S-EPMC5388155 | biostudies-literature
Project description:We report investigations on the influences of post-deposition treatments on the performance of solution-processed methylammonium lead triiodide (CH₃NH₃PbI₃)-based planar solar cells. The prepared films were stored in pure N₂ at room temperature or annealed in pure O₂ at room temperature, 45°C, 65°C and 85°C for 12 hours prior to the deposition of the metal electrodes. It is found that annealing in O₂ leads to substantial increase in the power conversion efficiencies (PCEs) of the devices. Furthermore, strong dependence on the annealing temperature for the PCEs of the devices suggests that a thermally activated process may underlie the observed phenomenon. It is believed that the annealing process may facilitate the diffusion of O₂ into the spiro-MeOTAD for inducing p-doping of the hole transport material. Furthermore, the process can result in lowering the localized state density at the grain boundaries as well as the bulk of perovskite. Utilizing thermal assisted O₂ annealing, high efficiency devices with good reproducibility were attained. A PCE of 15.4% with an open circuit voltage (VOC) 1.04 V, short circuit current density (JSC) 23 mA/cm(2), and fill factor 0.64 had been achieved for our champion device.
| S-EPMC4208060 | biostudies-literature
Project description:CH3NH3PbI3 capped PbS colloidal quantum dots have been successfully fabricated by solid-state ligand exchange from oleate and oleylamine capped PbS. The optimal solar cells made by layer-by-layer solution deposition give a high power conversion efficiency of 4.25% with an impressive short-circuit photocurrent density of 24.83 mA cm-2.
| S-EPMC5067684 | biostudies-literature
Project description:A mesoscopic methylammonium lead iodide (CH?NH?PbI?) perovskite/TiO? heterojunction solar cell is developed with low-cost carbon counter electrode (CE) and full printable process. With carbon black/spheroidal graphite CE, this mesoscopic heterojunction solar cell presents high stability and power conversion efficiency of 6.64%, which is higher than that of the flaky graphite based device and comparable to the conventional Au version.
| S-EPMC3816285 | biostudies-literature
Project description:Halide perovskite (HaP) semiconductors are revolutionizing photovoltaic (PV) solar energy conversion by showing remarkable performance of solar cells made with HaPs, especially tetragonal methylammonium lead triiodide (MAPbI3). In particular, the low voltage loss of these cells implies a remarkably low recombination rate of photogenerated carriers. It was suggested that low recombination can be due to the spatial separation of electrons and holes, a possibility if MAPbI3 is a semiconducting ferroelectric, which, however, requires clear experimental evidence. As a first step, we show that, in operando, MAPbI3 (unlike MAPbBr3) is pyroelectric, which implies it can be ferroelectric. The next step, proving it is (not) ferroelectric, is challenging, because of the material's relatively high electrical conductance (a consequence of an optical band gap suitable for PV conversion) and low stability under high applied bias voltage. This excludes normal measurements of a ferroelectric hysteresis loop, to prove ferroelectricity's hallmark switchable polarization. By adopting an approach suitable for electrically leaky materials as MAPbI3, we show here ferroelectric hysteresis from well-characterized single crystals at low temperature (still within the tetragonal phase, which is stable at room temperature). By chemical etching, we also can image the structural fingerprint for ferroelectricity, polar domains, periodically stacked along the polar axis of the crystal, which, as predicted by theory, scale with the overall crystal size. We also succeeded in detecting clear second harmonic generation, direct evidence for the material's noncentrosymmetry. We note that the material's ferroelectric nature, can, but need not be important in a PV cell at room temperature.
| S-EPMC5514731 | biostudies-literature