All-solution-processing at low temperatures is important and desirable for making printed photovoltaic devices and also offers the possibility of a safe and cost-effective fabrication environment for the devices. Herein, an all-solution-processed flexible organic solar cell (OSC) using poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) electrodes is reported. The all-solution-processed flexible devices yield the highest power conversion efficiency of 10.12% with high fill factor of over 70%, which is the highest value for metal-oxide-free flexible OSCs reported so far. The enhanced performance is attributed to the newly developed gentle acid treatment at room temperature that enables a high-performance PEDOT:PSS/plastic underlying substrate with a matched work function (≈4.91 eV), and the interface engineering that endows the devices with better interface contacts and improved hole mobility. Furthermore, the flexible devices exhibit an excellent mechanical flexibility, as indicated by a high retention (≈94%) of the initial efficiency after 1000 bending cycles. This work provides a simple route to fabricate high-performance all-solution-processed flexible OSCs, which is important for the development of printing, blading, and roll-to-roll technologies.

The privileged spiro[pyrrolidin-3,3'-oxindole] derivatives exhibit important biological activities. An enantioselective organocatalytic approach to the rapid synthesis of spiro[pyrrolidin-3,3'-oxindole] derivatives with high enantiopurity and structural diversity is described. The asymmetric catalytic three-component 1,3-dipolar cycloaddition of a broad range of methyleneindolinones with aldehydes and amino esters in the presence of chiral phosphoric acid provides spirooxindole derivatives in high yield with unusual regiochemistry and excellent stereoselectivities (up to 98% ee) under mild conditions. The straightforward construction of spirooxindole skeletons with high stereo- and regioselectivity suggests a new avenue to medicinal chemistry and diversity-oriented synthesis. Theoretical calculations disclosed that both the azomethine ylide and the methyleneindolinone are hydrogen-bonded with the phosphoric acid, which accounted for the high enantio- and regioselectivity and indicated that the unusual regioselectivity results from the stabilization stemming from the favorable pi-pi stacking interaction between the oxo-indole ring and the conjugated esters.

A visible-light photocatalytic generation of N-centered hydrazonyl radicals has been accomplished for the first time. This approach allows efficient intramolecular addition of hydrazonyl radical to terminal alkenes, thus providing hydroamination and oxyamination products in good yields. Importantly, the protocol involves deprotonation of an N-H bond and photocatalytic oxidation to an N-centered radical, thus obviating the need to prepare photolabile amine precursors or the stoichiometric use of oxidizing reagents.