Journal of the American Chemical Society最新文献

Self-assembled monolayer molecules have been widely employed as interfacial transport materials in inverted perovskite solar cells (PSCs), demonstrating high efficiency and improved device stability. However, self-assembling monolayer (SAM) molecules often suffer from aggregation and weak interactions with the perovskite layer, resulting in inefficient charge transfer and significant energy losses, ultimately limiting the power conversion efficiency and long-term stability of perovskite solar cells. In this work, we developed a series of novel skeleton-matching carbazole isomer SAMs based on the following key design principles: (1) introducing a benzene ring structure to distort the molecular skeleton of the SAM, thereby preventing aggregation and achieving a uniform distribution on fluorine-doped tin oxide (FTO) substrates; (2) strategically incorporating methoxy groups onto the benzene ring at different positions (ortho, meta, and para). These functional groups not only increase anchoring points with the perovskite layer but also fine-tune the molecular dipole moment. Among the SAMs, m-PhPACz exhibits the most favorable properties, with a maximum dipole moment of 2.4 D and an O-O distance that aligns excellently with the diagonal lead ions in the adjacent perovskite lattice, thereby enhancing SAM-perovskite interactions, facilitating efficient charge extraction, and improving interfacial stability. As a result, the new SAM-based PSCs achieved an impressive power conversion efficiency of 26.2%, with 12.9% improvement. Moreover, the devices demonstrated outstanding photothermal stability, retaining 96% of their initial PCE after 1000 h at 85 °C and maintaining 90% of their initial PCE after 300 h of UV-light exposure.

The synthesis of alkylated indoles, which are key intermediates for various drugs and bioactive molecules, is of great importance. However, most reports on the synthesis of functionalized indoles use toxic and expensive 4d or 5d metal catalysts, limiting the further application of these methods. Herein, we disclose a versatile regioselective C–H alkylation of indole derivatives using a well-defined three-coordinate iron(0) complex. Neither Grignard reagents nor additional additives are required, making the reaction sustainable, environmentally friendly, and compatible with a broad variety of functional groups to afford C2-alkylated indoles in high yields. In addition, by variation of the aryl substituent on the alkene substrate to the trisubstituted silyl group, the regioselectivity of the C–H alkylation can be altered from Markovnikov to anti-Markovnikov. Detailed mechanistic studies further revealed the catalytic mode of reaction.

A wide variety of reactions are reported to be dramatically accelerated in aqueous microdroplets, making them a promising platform for environmentally clean chemical synthesis. However, to fully utilize the microdroplets for accelerating chemical reactions requires a fundamental understanding of how microdroplet chemistry differs from that of a homogeneous phase. Here we provide our perspective on recent progress to this end, both experimentally and theoretically. We begin by reviewing the many ways in which microdroplets can be prepared, creating water/hydrophobic interfaces that have been frequently implicated in microdroplet reactivity due to preferential surface adsorption of solutes, persistent electric fields, and their acidity or basicity. These features of the interface interplay with specific mechanisms proposed for microdroplet reactivity, including partial solvation, possible gas phase channels, and the presence of highly reactive intermediates. We especially highlight the role of droplet charge and associated electric fields, which appears to be key to understanding how certain reactions, like the formation of hydrogen peroxide and reduced transition metal complexes, are thermodynamically possible in microdroplets. Lastly, we emphasize opportunities for theoretical advances and suggest experiments that would greatly enhance our understanding of this fascinating subject.