Dopamine Hydrochloride-Assisted Synergistic Modulation of Perovskite Crystallization and Sn2+ Oxidation for Efficient and Stable Lead-free Solar Cells.

Tin perovskites have received great concern in solar cell research owing to their favorable optoelectronic performance and environmental friendliness. However, due to their poor crystallization and easy oxidation, the performance improvement for tin-based perovskite solar cells (TPSCs) is rather challenging. Herein, reductive 3-hydroxytyramine hydrochloride (DACl) with NH2·HCl and phenol groups as co-additives with SnF2 is added into the precursor to modulate perovskite crystallization and inhibit Sn2+ oxidation for high-performance TPSCs. The Lewis base group of NH2 HCl in DACl could bind to perovskite lattices to modulate the crystallization with suppressed defects in the bulk and grain boundary, whereas reductive phenol groups effectively constrain the Sn2+ oxidation. Moreover, the undissociated DACl decreases the supersaturated concentration of tin perovskite solution and creates a pre-nucleation site for rapid nucleation to further regulate crystallization. Consequently, the DACl-derived TPSCs achieve a high power-conversion efficiency (PCE) that reaches up to 11%. More impressively, the device remains at 84% of the initial PCE after full-sun illumination in N2 over 600 h without being encapsulated. This DACl-based synergistic modulation of a lead-free perovskite demonstrates a feasible approach using one molecule with different functional groups to manipulate crystallization, Sn2+ oxidation, and defect reparation of tin perovskite films, providing a critical guideline for constructing high-quality perovskites by multifunctional additives with high photovoltaic performance.

Palladium-Catalyzed Catellani ortho-Acylation Reaction: An Efficient and Regiospecific Synthesis of Diaryl Ketones.

A palladium-catalyzed, norbornene-mediated Catellani ortho-acylation reaction was developed by the use of either acyl chlorides or acid anhydrides as acylation reagents. The addition of more than a stoichiometric amount of H2 O is crucial for this transformation when acid chlorides are used, and kinetic studies indicate that the active acylation reagent is possibly an acid anhydride.

Palladium-catalyzed intramolecular asymmetric C-H functionalization/cyclization reaction of metallocenes: an efficient approach toward the synthesis of planar chiral metallocene compounds.

A palladium-catalyzed asymmetric synthesis of planar chiral metallocene compounds is reported. The reaction stereoselectively functionalized one of the ortho C-H bonds of Cp rings by intramolecular cyclization to form indenone derivatives in high yields with excellent enantioselectivity. The mild set of reaction conditions allowed a wide variety of chiral metallocene compounds to be synthesized with broad functional group tolerance. The influences of preinstalled chiralities on the other Cp-ring were also investigated.

Pd-catalyzed Heck-type cascade reactions with N-tosyl hydrazones: an efficient way to alkenes via in situ generated alkylpalladium.

A palladium-catalyzed Heck-type cascade reaction of aryl halides and N-tosyl hydrazones is reported. The neopentylpalladium species, generated from an intramolecular Heck-type insertion reaction of aryl halides, could efficiently react with carbenes to form highly functionalized alkenes. The synthesis of spiro compounds was also explored via a multiple Heck-type insertion reaction with N-tosyl hydrazone.