Enlarging grain sizes for efficient perovskite solar cells by methylamine chloride assisted recrystallization

The quality of MAPbI3 film prepared by solvent engineering process highly depends on environment and antisolvent control.Here,we provided a simple methylamine chloride(MACl)solution treatment using a two-step process to enlarge the perovskite crystal grain sizes to more than 1 lm.Other than treatment on the film surface,the MACl solution diffuses into the MAPbI_(3) films to assist the recrystallization of small crystal at the bottom of perovskite film.The imitative contact between perovskite and substrate is formed.Meanwhile,the enlargement of grain size and ten times enhancement of crystalline reduce trap-assisted recombination of perovskite films.Thus,the significant improvement of cell efficiency of 20.89%as well as device stability is obtained with the MACl treatment.

Decomposition of methylamine on Mo(100) surface: A DFT study

The initial decomposition of methylamine on Mo（100） surface has been investigated by self-consistent （GGA-PW91） density functional theory combined with periodic slab model. The adsorption energies of possible species and the activation energies for possible elementary reactions involved are obtained in the present work. Our results indicate that the barriers decreased with the order of C-NN-HC-H. In addition, metastable adsorption of the abstracted hydrogen atom on the hollow site in the final state is also considered for the N-H and C-H bond breaking. For the C-H bond cleavage, the reaction barrier that the abstracted hydrogen located on the hollow site in the final state is lower than that on the bridge site. However, for the N H bond breaking, the barriers are alike for the abstracted hydrogen on both hollow and bridge sites in the final state.

Understanding the precursor chemistry for one-step deposition of mixed cation perovskite solar cells by methylamine route

Upscaling perovskite solar cell fabrication is one of the key challenges in the pathway for commercialization.The slow evaporation of frequently used solvents(DMF or DMSO) limits the fast perovskite layer crystallization,hindering their implementation in large scale deposition methods.Alternatively,methylamine-based precursors have demonstrated rapid crystallization,leading to uniform and specular films.Nonetheless,their application has been limited to MAPbI3 perovskites with limited efficiency and stability.In this work,we report the requirements for stabilizing α-phase of mixed cation perovskites with high amount of formamidinium by using a methylamine-based precursor.We found that even though,there are many methods for incorporating the methylamine(MA) in precursors or films;the MA content determines stabilization of the α-phase and therefore the viscous-solution route is the only method to incorporate high amounts of MA.At low amounts of MA,perovskite tend to crystallize in 1D dimensional FA_(3)(MA)PbI5 phases due to the incomplete solvation of the PbI6-clusters.In contrast,high MA ratio induces a full solvation of the clusters,leading to a rapid crystallization and a full stabilization of the active 3D α-phase.These results open a window in the development and understanding of new precursors for the fabrication of high efficient,stable and scalable perovskite devices.

Synthesis, Characterization and Cytotoxicity of Ammine/Methylamine Platinum(Ⅱ) Complexes with Carboxylates

Seven novel platinum （Ⅱ） complexes [ Pt（Ⅱ） （NH3） （CH3NH2）X2] （Ⅰ-Ⅶ ） （ X： CH3COO^-, CH2CICOO^- , CHCI2COO^- , C6H5-COO^- , p-CH3O--C6H4-COO^- , p-NH2-C6H4-COO^- , p-NO2--C6H4- COO^-） were prepared and characterized by means of elemental analysis, molar conductivity, thermal analysis, IR, UV, and ^1H NMR spectrometries. The cytotoxicity against HCT-8, BGC-823, MCF-7, EJ, and HL-60 cell lines increases in the following sequence： cisplatin 〉 Ⅳ 〉 Ⅴ 〉 Ⅵ 〉 Ⅶ 〉 Ⅰ 〉 Ⅱ 〉 Ⅲ. Moreover, the complexes （ Ⅰ --Ⅻ） display substantially greater activities agaist EJ and HL-60 cell lines than those against the cell lines from other carcinomas. They can induce a concentration-dependent accumulation of HL-60 cells in the G2/M phase of the cell cycle as cisplatin. There is no significant correlation between total DNA platination levels and cytotoxicity of the complexes.

THE SEPARATIONS OF ENANTIOMERS OF α—SUBSTITUTED-(2—PYRIDYL)—METHYLAMINES ON A CHIRASIL-VAL CAPILLARY COLUMN

Enantiomers of a-substituted-(2-pyridyl)-methylarfdnes uere separated on SC -7 gas chromatograph with a 20m×0.25mm Chirasil-Val capIlary column,Carrier gas was nitro- gen or hydrogen.The resolution factors(ri.s) were 1.02 to 1.06.Enantiomers of pyridyl anines were separated to and near to base line.

Formation of halonitromethanes from methylamine in the presence of bromide during UV/Cl2 disinfection

The UV/Clprocess is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of hightoxic halonitromethanes(HNMs) in the presence of bromide ions(Br-) during UV/Cldisinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br-. An excessively high concentration of Br-induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor(BIF) increased, while the maximum bromine utilization factor(BUF) decreased with the increase of Br-concentration. The maximum yield of HNMs decreased as p H value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while p H value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl:Br-ratio of 12.5, whereas the BIF value remained relatively higher at low Cl:Br-ratios(2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation(especially brominated species) when the UV/Clprocess is adopted as a disinfection technique.

A DFT＋U Investigation on Methylamine Decomposition Catalyzed by Pt4 Cluster Supported on Oxygen Defective Rutile（110） TiO2

The adsorption and decomposition mechanisms of methylamine catalyzed by Pt4 cluster supported on ruffle（110） titania[namely, Pt4/TiO2-R（110）] were investigated via density functional theory slab calculations with Hubbard corrections（DFT＋U）. The adsorption energies under the most stable configuration of the possible species and the energy barriers of the possible elementary reactions involved in methylamine decomposition were obtained. Through systematic calculations for the reaction mechanism of methylamine decomposition on the PtVTiO2-R（110）, the most possible decomposition path is CHaNH2→CH2NH2＋H→CH2NH＋2H→CHNH＋3H→HCN＋4H→CN＋5H, which is similar to that of methylamine dissociation catalyzed by Pt（100） surface.

Organic salt mediated growth of phase pure and stable all-inorganic CsPbX3（X = I, Br） perovskites for efficient photovoltaics

All-inorganic CsPbX3(X = I, Br) perovskites without organic component are promising for long-term stability but face main challenges of facile fabrication and phase stability. Here we discover a general organic methylamine acetate salt mediated growth method to deposit high quality phase pure and stable CsPbX3(X = I, Br) perovskite films via a novel precursor consisting of stoichiometric cesium acetate(CsAc),methylamine halide(MAX) and lead halide(PbX2). Interestingly, these organic salts of CsAc and MAX could efficiently promote the crystallization process especially lower the crystallization temperature,but do not introduce the incorporation of organic MA cation into all-inorganic CsPbX3 perovskites.These phase pure and stable CsPbX3 perovskites with tunable band gaps can be fabricated into high efficiency photovoltaics. Our organic salt mediated growth of all-inorganic perovskite not only reveals the all-inorganic CsPbX3 perovskite’s unique crystal growth mechanism but also demonstrates their promising application for photovoltaics.

One-pot Synthesis of lO-Methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-l,8-dione Derivatives under Microwave Heating without Catalyst

A series of 10-methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives were synthesized by one-pot reaction of aldehyde, dimedone or 1,3-cyclohexanedione and methylamine in glycol or water under microwave heating without catalyst. The method has the advantage of short routine and reaction time, high yields as well as friendly environment. And the reaction was not only suitable for aliphatic and aromatic monoaldehyde, but also for aromatic dialdehyde.