Interfacial modification of organolead halide perovskites (OHPs) has shown to be a promising strategy to improve the quality of OHPs film. In this work, a bipolar amino acid molecule, L‐Leucine (LL), have been introduced to the anti‐solvent solution to induce the formation methylammonium lead triiodide (MAPbI3) perovskite films. The morphology, crystal structure, and optoelectronic property of perovskite films are systematically studied, where the bipolar LL plays a key role. By employing the LL‐modified perovskite film, the perovskite solar cells (PSCs) are well prepared. Consequently, a 18.2% efficiency was obtained from the champion device, which showed a significant improvement compared to the controlled device with a PCE of 16.1%. Our results demonstrate the crucial role of bipolar feature of interfacial modification agent on the charge transfer at the interface, and provide important interfacial modification concept on efficient PSCs. Moreover, significantly improved stability can be observed from the LL modified devices, benefiting from the effectively trap‐passivation.
We present a theoretical study of the terahertz-pulse-induced intraexcitonic dynamics of optically created excitons in quantum wells, providing an explanation of the density dependence of the 1s-2p intraexcitonic transitions observed experimentally. We find that two types of many-body interactions, the phase space filling and the exchange interaction, are responsible for the observed red-shift of the resonance frequency. In addition to calculating the density renormalized exciton energy levels, which offer indirect information regarding the density-dependent 1s-2p transitions, we developed a mean-field approach to examine the intraexcitonic transition process directly. The resulting dynamic equation provides a useful tool to gain insight into the intraexcitonic transitions in semiconductor nanostructures.
Based on different reactivity of the (pseudo)halide substituents in the 2-pyrone (3-Br and 4-OTs), palladium-catalyzed sequential site-selective Suzuki-Miyaura cross-coupling reactions of 3-bromo-6-methyl-4-tosyloxy-2-pyrone are described, which afford the diverse 2-pyrones in good yields.
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