Since Michael Faraday and Joseph Henry made their great discovery of electromagnetic induction, there have been continuous developments in electrical power generation. Most people today get ...electricity from thermal, hydroelectric, or nuclear power generation systems, which use this electromagnetic induction phenomenon. Here we propose a new method for electrical power generation, without using electromagnetic induction, by mechanically modulating the electrical double layers at the interfacial areas of a water bridge between two conducting plates. We find that when the height of the water bridge is mechanically modulated, the electrical double layer capacitors formed on the two interfacial areas are continuously charged and discharged at different phases from each other, thus generating an AC electric current across the plates. We use a resistor-capacitor circuit model to explain the results of this experiment. This observation could be useful for constructing a micro-fluidic power generation system in the near future.
We demonstrate cesium-doping in methylammonium lead iodide perovskites (CsxMA1−xPbI3) light absorbers to improve the performance of inverted-type perovskite/fullerene planar heterojunction hybrid ...solar cells. CsxMA1−xPbI3 perovskite devices with an optimized 10% Cs doping concentration exhibit remarkable improvement in device efficiency from 5.51% to 7.68% due to increases in short-circuit current density and open-circuit voltage via increased light absorption at optimum device thickness, improved film morphology and a widening of the energy difference between the valence band of the perovskite and lowest unoccupied molecular orbital level of PCBM.
Cesium-doped methylammonium lead iodide perovskites are developed as light absorbers for inverted-type perovskite/fullerene planar heterojunction hybrid solar cells. Cesium doping remarkably improves device efficiency from 5.51% to 7.68% due to increases in JSC and VOC via improved light absorption, film morphology and a widening of the energy difference between the valence band of the perovskite and LUMO level of PCBM. Display omitted
•We have synthesized cesium-doped methylammonium lead iodide perovskite for light absorber.•We fabricate inverted-type perovskite/PCBM hybrid solar cells using cesium-doped perovskite.•Cesium doping in perovskite results in improvements in light absorption and morphology.•Cesium-doped perovskite leads to remarkable enhancement in performance of hybrid solar cells.
We investigate mixed solvents of N,N-dimethylformamide (DMF) and γ-butyrolactone (GBL) to produce the smooth surface of a perovskite film and uniform crystal domains. This ideal morphology from mixed ...solvents enhances the power conversion efficiency to over 6% by improving the exciton dissociation efficiency and reducing the recombination loss at both interfaces of PEDOT:PSS/perovskite and perovskite/PCBM.
Organic-inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although ...efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidic
PSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative to
PSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells.
Abstract
We report the extraction of silicon via a carbothermal reduction process using a CO
2
laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown ...after laser beam irradiation for a few tens of seconds, and clear peaks of crystalline silicon were observed by Raman shift measurements, confirming the successful carbothermal reduction of silica. The influence of process parameters, including the laser beam intensity, radiation time, nitrogen gas flow in a reaction chamber, and the molar ratios of silica/carbon black of the mixture, on the carbothermal reduction process is explained in detail.
Edged-selectively fluorine (F) functionalized graphene nanoplatelets (EFGnPs-F) with a p–i–n structure of perovskite solar cells achieved 82% stability relative to initial performance over 30 days of ...air exposure without encapsulation. The enhanced stability stems from F-substitution on EFGnPs; fluorocarbons such as polytetrafluoroethylene are well-known for their superhydrophobic properties and being impervious to chemical degradation. These hydrophobic moieties tightly protect perovskite layers from air degradation. To directly compare the effect of similar hydrophilic graphene layers, edge-selectively hydrogen functionalized graphene nanoplatelet (EFGnPs-H) treated devices were tested under the same conditions. Like the pristine MAPbI3 perovskite devices, EFGnPs-H treated devices were completely degraded after 10 days. The hydrophobic properties of EFGnPs-F were characterized by contact angle measurement. The test results showed great water repellency compared to pristine perovskite films or EFGnPs-H coated films. This resulted in highly air-stable p–i–n perovskite solar cells.
CsPbX3 (X = I, Br, Cl) perovskite nanocrystals (NCs) have recently emerged as emitting materials for optoelectronic and display applications owing to their easily tunable emissions, high ...photoluminescence quantum yield (PLQY), and vivid color purity (full width at half maximum of approximately 20 nm). However, the lagging quantum yields of blue-emitting perovskite NCs have resulted in low efficiency compared to green or red perovskite light-emitting diodes (PeLEDs); moreover, the long insulating ligands (such as oleylamine and oleic acid) inhibit charge carrier injection. In this study, we demonstrated a facile ligand-mediated post-treatment (LMPT) method for high-quality perovskite NCs with changing optical properties to allow fine-tuning of the target emission wavelength. This method involves the use of a mixed halide ion-pair ligand, di-dodecyl dimethyl ammonium bromide, and chloride, which can induce a reconstruction through a self-anion exchange. Using the LMPT method, the PLQY of the surface-passivated blue-emitting NCs was dramatically enhanced to over 70% within the 485 nm blue emission region and 50% within the 467 nm deep-blue emission region. Through this treatment, we achieved highly efficient blue-PeLED maximum external quantum efficiencies of 0.44 and 0.86% within the 470 and 480 ± 2 nm electroluminescence emission regions, respectively.
Significant aggregation between ZnO nanoparticles (ZnO NPs) dispersed in polar and nonpolar solvents hinders the formation of high quality thin film for the device application and impedes their ...excellent electron transporting ability. Herein a bifunctional coordination complex, titanium diisopropoxide bis(acetylacetonate) (Ti(acac)
) is employed as efficient stabilizer to improve colloidal stability of ZnO NPs. Acetylacetonate functionalized ZnO exhibited long-term stability and maintained its superior optical and electrical properties for months aging under ambient atmospheric condition. The functionalized ZnO NPs were then incorporated into polymer solar cells with conventional structure as n-type buffer layer. The devices exhibited nearly identical power conversion efficiency regardless of the use of fresh and old (2 months aged) NPs. Our approach provides a simple and efficient route to boost colloidal stability of ZnO NPs in both polar and nonpolar solvents, which could enable structure-independent intense studies for efficient organic and hybrid optoelectronic devices.
Delphinidin (DP), an anthocyanidin found in blueberries, has antioxidant and anti-inflammatory effects. This study aimed to investigate the efficacy of DP as a storage medium for avulsed teeth.
Human ...periodontal ligament cells were cultured and exposed to DP solution (10, 50, and 100 μM), Dulbecco's modified Eagle's medium, Hank's balanced salt solution and tap water. Cell counting kit-8 assays were performed after 0.5, 1, 6, and 24 h to measure the cell viability. Nitric oxide assays and gelatin zymography were performed to evaluate the anti-inflammatory effects of DP. Reverse transcription-polymerase chain reaction was used to determine the expression levels of inflammatory cytokines.
The viability of periodontal ligament cells was greatest at 100 μM DP. At 1 h, 100 μM DP decreased nitric oxide synthesis (p < .0167). Matrix metallopeptidase-9 activity was inhibited by DP in a dose-dependent manner (p < .0167). Moreover, treatment with 100 μM DP decreased the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 in periodontal ligament cells (p < .0167).
Within the limits of this study, DP preserved the viability and suppressed the inflammatory response of periodontal ligament cells. These findings suggest that DP could be promising for preservation of avulsed teeth.
We demonstrate a practical route to synthesize Ge nanoparticles (NPs) in multi-gram quantities
via
the laser pyrolysis of GeH
4
gas. The size of the as-produced Ge NPs can be precisely controlled in ...the range of 19.0 to 65.9 nm
via
a subsequent etching procedure using a dilute H
2
O
2
solution. Stable water dispersions of Ge NPs yield particles with a Ge/GeO
2
core-shell structure, however, the oxide shell can easily be removed and passivated by treatment with HCl. The feed materials used in this process are readily available and lead to non-toxic, water-based dispersions of Ge NPs. The scalability and convenience of this procedure make it attractive as a method to obtain Ge NP dispersions for use in applications such as optoelectronic devices and biosensors.
Facile and precise tailoring of the size (∼19-65 nm) of germanium nanoparticles synthesized by laser pyrolysis of GeH
4
is demonstrated using a dilute hydrogen peroxide solution.
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