Synthesis of Isothiazoles and Isoselenazoles through Rhodium-Catalyzed Oxidative Annulation with Elemental Sulfur and Selenium.

A rhodium-catalyzed oxidative annulation of benzimidates with elemental sulfur for the direct construction of isothiazole rings is reported. The proposed reaction mechanism involving Rh(I)/Rh(III) redox is supported by a stoichiometric reaction of metallacycle species as well as DFT calculations. This method is also applicable to selenium cyclization to produce isoselenazole derivatives. The alkoxy substituent at C3 can be used for further functionalization of the azole core.

Thioether-Directed Peri-Selective C-H Arylation under Rhodium Catalysis: Synthesis of Arene-Fused Thioxanthenes.

A rhodium-catalyzed direct C-H arylation of naphthalene and anthracene was developed with the assistance of a thioether directing group. The reaction proceeded with exclusive peri-selectivity, and the series of coupling products were readily transformed into the corresponding sulfur-containing polyaromatics. Charge-transport properties of the provided dithiapyrenes were evaluated by computational studies.

Field Emission and Electrical Properties of Perovskite.

We investigate characteristic field emission properties of methyl ammonium mixed-halide perovskite (CH3NH3PbI3-xClx) and their current change under one laser pulse. To analyze these properties, we fabricated inverted-type mixed-halide perovskite solar cells which exhibit a device efficiency of 9.31% under A.M 1.5 condition. Under one laser pulse varying from 420 nm to 580 nm, perovskite layer considerably reacted from 420 nm to 440 nm and then gradually decreased in current. A turnon field of 5.56 V and a field enhancement factor of 3183 were obtained from one spin-coating perovskite layer and in eight times of perovskite spin-coating cycles, a turn-on field of 6.70 V and a field enhancement factor of 5110 were observed.

Hole transport layer based on conjugated polyelectrolytes for polymer solar cells.

We demonstrate the conjugated polyelectrolytes (CPEs) as efficient hole transport layer (HTL) of polymer solar cells. Replacing poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) with a CPEs with narrow bandgap results in both improvements in device efficiency and stability. In spite of their narrow bandgap, thin CPE films (thickness of ∼30 nm) enable sufficient light absorption within the active layer. Enhancement of device efficiency is attributed to low surface roughness, high transmittance in visible region, and reduced charge transfer resistance. Compared to the device with PEDOT:PSS, pH neutral nature of CPEs may enhance device stability under ambient condition.