Silver is a low‐cost candidate electrode material for perovskite solar cells. However, in such cells the silver electrodes turn yellow within days of device fabrication. The color change is also accompanied by a dramatic decrease in the power conversion efficiency when compared to otherwise identical devices using gold electrodes. Here, it is shown that the color change results from silver oxidation to silver iodide, due to a reaction with iodine in methyl ammonium lead perovskite. The change in X‐ray diffraction and X‐ray photo­electron spectroscopy is discussed. Exposure to air accelerates corrosion of the Ag electrodes when compared to dry nitrogen gas exposure. However, iodine not reacted with silver is observed by X‐ray photoelectron spectroscopy even for the perovskite solar cell kept in dry nitrogen gas. It is proposed that silver iodide is formed when methyl ammonium iodide migration is facilitated by the small pinholes in the hole transport layer spiro‐MeOTAD.

Organometal halide based perovskites are promising materials for solar cell applications and are rapidly developing with current devices reaching $19% efficiency. In this work we introduce a new method of perovskite synthesis by hybrid chemical vapor deposition (HCVD), and demonstrate efficiencies as high as 11.8%. These cells were found to be stable with time, and retained almost the same efficiency after approximately 1100 h storage in dry N 2 gas. This method is particularly attractive because of its ability to scale up to industrial levels and the ability to precisely control gas flow rate, temperature, and pressure with high reproducibility. This is the first demonstration of a perovskite solar cell using chemical vapor deposition and there is likely still room for significant optimization in efficiency.

In the last few years, lead halide perovskite solar cell power conversion efficiencies have risen by using a wide variety of fabrication methods and just passed 20%. Perovskite solar cells are typically fabricated in a glove box to strictly avoid any water exposure. A dry atmosphere significantly increases equipment and operational costs for industrial processes, so ambient perovskite fabrication will be less-expensive and more attractive. In this work it is demonstrated that ambient annealing is comparable to annealing in dry N 2 . Perovskite films annealed in a standard dry N 2 environment are compared with those annealed in ambient environment with 50% relative humidity. Solar cell devices were prepared with a planar structure configuration and annealed at one of three different temperatures (105, 115 or 125 C) in either N 2 or ambient air. For all temperatures, the average efficiencies for the devices annealed in air are higher than those annealed in dry N 2 . The highest efficiency achieved for air-annealed devices is 12.7%. Thus, good efficiency cells can be fabricated in an ambient environment, which facilitates mass production.

We report the development of instrumentation and methodology for fabricating large area semi-transparent organo-lead-halide perovskite films. In our method, the growth of perovskite films relies on the control of CH 3 NH 3 I flow and vapor pressure inside a vacuum chamber. Solar cell devices based on the prepared semi-transparent perovskite films as thin as $135 nm achieved an efficiency of 9.9% and a high open circuit voltage of 1.09 V.

We report the results of 1 ′ .5 × 3 ′ mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S 1.1 mm = 0.7 − 6.4 mJy (L IR ∼ 10 12.1 − 10 13.1 L ⊙ ) are at z = 3.08 − 3.10. Not only are these SMGs members of the protocluster but they in fact reside within the node at the junction of the 50 Mpc-scale filamentary three-dimensional structure traced by Lyman-α emitters (LAEs) in this field. The eight SMGs account for a star formation rate density (SFRD) ∼10 M ⊙ yr −1 Mpc −3 in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host a X-ray luminous active galactic nuclei (AGN). Our results suggest that the vigorous star formation activity and the growth of super massive black holes (SMBHs) occurred simultaneously in the densest regions at z ∼ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyman-α blobs (LABs), implying that the two populations coexist in high density environments for a few cases.

attractive approach to reach high energy density; however, the previously reported study has an environmental concern due to the use of heavy metals and lower energetic density caused by the bulky cations. [ 3 ] In addition, the liquids should have a stable fl uidic property even in a low temperature range without freezing, especially for automobile applications.Here, we propose to change the strategy from maximizing the solubility of redox compounds to minimizing the dissolving solvents (Figure 1 a, right side). The minimum requirements for the catholyte are stoichiometric couples of a redox species and appropriate supporting salt. Because the valence of the redox species must be changed during discharging and charging, compensating ions must be present in the system. Therefore, a redox couple with a single valence change (i.e., A/A + , A − /A, or A + /A ++ ) requires the same molar of monovalent salt (i.e., X + B − ), and their 1:1 molar mixture yields the maximum electronic capacity for batteries. The challenge is then determining how to liquefy this couple. First, we selected 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl ( MT or MeO-TEMPO) as a redox compound. MT has excellent chemical, physical, and electrochemical stability, [4] similar to non-substituted TEMPO, [ 5 ] and also has a low melting point ( T m ) (42 °C). Next, we focused on lithium bis(trifl uoromethanesulfonyl) imide ( LT or LiTFSI) as a supporting salt because TFSI anion was one of the most interesting ions with an unusual plasticizing effect, which often realized low T m mixtures, [ 6 ] plastic crystals [ 7 ] and supercooled liquids, whereas the T m of LT was rather high (230 °C). In previous studies, the unique effect has been understood by the weak Lewis-basic property due to its charge delocalization and isoenergetic conformation change. [ 8 ] Then, as shown in Figure 1 b (right side), a simple 1:1 molar mixture of MT and LT exhibited a self-melting behavior and formed a smooth viscous liquid. Finally, by the addition of small amount of an appropriate solvent (i.e., acetonitrile (ACN), water, etc.) a highly concentrated (over 2 M ) and low-viscosity liquid could be prepared (Figure 1 b, center). In this report, the mixture of MT and LT with molar ratios of x and y , respectively, will be described as " MTLT ( x / y )." For example, MTLT (1/1) denotes a 1:1 molar mixture of MT and LT . Mixtures ranging from MTLT (1/1) to MTLT (20/1) are found to yield orangecolored smooth liquids at room temperature. Because i) a series of sulfonylimide-based salts, such as Li bis(fl uorosulfonyl) imide (LiFSI) or Li bis(pentafl uoroethanesulfonyl) imide (LiBETI), exhibit similar properties and ii) other inorganic Li-salts, such as LiPF 6 , or LiBF 4 , do not exhibit this unique feature (Figure 1 b, left), the sulfonylimide structure could be critical to understanding this unique property. With regard to TEMPO, even non-substituted TEMPO forms a similar liquid when mixed with LT ; however, the liquid phase is not stable can be crystallized more easi...

We propose a catalytic cycle using the iodine-dimethylsulfoxide (I2-DMSO) complex for the realization of secondary Mg-O2 batteries. We have demonstrated that the Mg-O2 battery incorporating an I2-DMSO complex electrolyte showed evidence of being rechargeable.

Lithium titanium oxide Li[Li1/3Ti5/3]O4 (LTO) is regarded as an ideal electrode material for lithium-ion batteries because of its “zero-strain” characteristic, high thermal stability, and structural stability. Here, the zero-strain means that the change in cubic lattice parameter is negligibly small during charge and discharge reactions. We performed ex situ Raman spectroscopy on Li1+x [Li1/3Ti5/3]O4 samples with 0 ≤ x ≤ 0.94 to gain information about the relationship between a zero-strain reaction scheme and structural change at the atomic scale. The x = 0 (initial) sample exhibits three major Raman bands at 671, 426, and 231 cm–1 and six minor Raman bands at 751, 510, 400, 344, 264, and 146 cm–1. According to Raman spectroscopy results on other lithium titanium oxides such as Li2TiO3 and TiO2, the Raman bands at 510, 400, and 146 cm–1 are attributed to TiO2 anatase, which is used as a starting material. As x increases from 0 to 0.94, the two major Raman bands at 426 and 231 cm–1 show a blue shift, while the major Raman band at 671 cm–1 maintains frequency. The three major Raman bands at 671, 423, and 231 cm–1 are assigned to the A 1g mode of symmetric stretching vibration νsym(Ti–O), the E g mode of asymmetric stretching vibration νasym(Li–O), and the F 2g mode of bending vibration δ(Ti–O), respectively. Thus, the change in the Raman spectrum with x indicates that the bond length between the Ti and O atoms in the TiO6 octahedron is independent of x, while that between the Li and O atoms in the LiO6 octahedron and the bond angle between the Ti and O atoms in the TiO6 octahedron change with x. Raman studies with decreasing x from 0.94 to 0.10 clarified that such local structural changes are reversible, as in the case for the electrochemical reaction. The zero-strain insertion scheme is discussed from the perspective of Raman spectroscopy.