Designed Additive to Regulated Crystallization for High Performance Perovskite Solar Cell.

It is a crucial role for enhancing the power conversion efficiency (PCE) of perovskite solar cells (PSCs) to prepare high-quality perovskite films, which can be achieved by delaying the crystallization of perovskite film. Hence, we designed difluoroacetic anhydride (DFA) as an additive to regulating crystallization process thus reducing defect formation during perovskite film formation. It was found DFA reacts with DMSO by forming two molecules, difluoroacetate thioether ester (DTE) and difluoroacetic acid (DA). The strong bonding DTE⋅PbI2 and DA⋅PbI2 retard perovskite crystallization process for high-quality film formation, which was monitored through in situ UV/Vis and PL tests. By using DFA additives, we prepared perovskite films with high-quality and low defects. Finally, a champion PCE of 25.28 % was achieved with excellent environmental stability, which retained 95.75 % of the initial PCE after 1152 h at 25 °C under 25 % RH.

P Doped MoO3-x Nanosheets as Efficient and Stable Electrocatalysts for Hydrogen Evolution.

A P doped MoO3-x nanocomposite material with rich oxygen vacancies is successfully fabricated by a two-step intercalation method, which presents superior activity for the hydrogen evolution reaction with low overpotential and fast electron transfer. In 0.5 m H2 SO4 , it displays an overpotential of 166 mV for driving the current density of 10 mA cm-2 . Moreover, it also shows a good catalytic stability in the electrolytes with different pH, 0.5 m H2 SO4 (strong acid), 0.5 m Na2 SO4 (neutral solution), and 0.1 m NaOH (strong base). The superior catalytic activity and stability are due to to the synergistic effect between the P element doping and the oxygen vacancies.

Transition-Metal-Free Synthesis of 1,3-Butadiene-Containing π-Conjugated Polymers.

This work describes the synthesis of π-conjugated polymers possessing arylene and 1,3-butadiene alternating units in the main chain by the reaction of α,ß-unsaturated ester/nitrile containing γ-H with aromatic/heteroaromatic aldehyde compound. By using 4-(4-formylphenyl)-2-butylene acid ethyl ester as a model monomer, the different polymerization conditions, including catalyst, catalyst amount, and solvent, are optimized. The polymerization of 4-(4-formylphenyl)-2-butylene acid ethyl ester is carried out by refluxing in ethanol for 72 h with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst to give a 1,3-butadiene-containing π-conjugated polymer, poly(phenylene-1,3-butadiene), in 84.3% yield with M¯n and M¯w/M¯n (PDI) estimated as 6172 and 1.65, respectively. Based on this new methodology, a series of π-conjugated polymers containing 1,3-butadiene units with different substituents are obtained in high yields. A possible mechanism is proposed for the polymerization through a six-membered ring transition state and then a 1,5-H shift intermediate.

Characterization of the adsorption of omega-(thiophene-3-yl alkyl) phosphonic acid on metal oxides with AR-XPS.

The aim of the work discussed in this paper was to characterize adsorbed self-assembled monolayers on different metal oxide substrates with angle-resolved XPS measurements. The substrates used were silicon wafers (100) coated with 300 nm Al, Ta, or Ti. They were coated with acids by immersing them in an ethanol solution. The orientation of long-chain organic acids adsorbed on metal oxides has been successfully identified by angle-resolved XPS. On Al, Ta, and Ti substrates, C(11) chains are orientated in the right manner, i.e. with the phosphonic group at the bottom and the thiophene group on top. The orientations of the C(2) and C(6) chains are not clear. The thickness of the layers could be obtained by using Tougaard nanostructure analysis, and it shows monolayers. A model of the chemical bonds between the phosphonic group and the metal could be developed from the chemical shift. For titanium, all three P-O bonds bind to the metal substrate, whereas only the P-O(H) bond binds to the metal on aluminium and tantalum.