Anchoring Vertical Dipole to Enable Efficient Charge Extraction for High-Performance Perovskite Solar Cells.

Perovskite solar cells (PSCs) via two-step sequential method have received great attention in recent years due to their high reproducibility and low processing costs. However, the relatively high trap-state density and poor charge carrier extraction efficiency pose challenges. Herein, highly efficient and stable PSCs via a two-step sequential method are fabricated using organic-inorganic (OI) complexes as multifunctional interlayers. In addition to reduce the under-coordinated Pb2+ ions related trap states by forming interactions with the functional groups, the complexes interlayer tends to form dipole moment which can enhance the built-in electric field, thus facilitating charge carrier extraction. Consequently, with rational molecular design, the resulting devices with a vertical dipole moment that parallels with the built-in electric field yield a champion efficiency of 23.55% with negligible hysteresis. More importantly, the hydrophobicity of the (OI) complexes contributes to an excellent ambient stability of the resulting device with 91% of initial efficiency maintained after 3000 h storage.

Oxalate Pushes Efficiency of CsPb0.7 Sn0.3 IBr2 Based All-Inorganic Perovskite Solar Cells to over 14.

All-inorganic CsPbIBr2 perovskite solar cells (PSCs) have recently gained growing attention as a promising template to solve the thermal instability of organic-inorganic PSCs. However, the relatively low device efficiency hinders its further development. Herein, highly efficient and stable CsPb0.7 Sn0.3 IBr2 compositional perovskite-based inorganic PSCs are fabricated by introducing appropriate amount of multifunctional zinc oxalate (ZnOX). In addition to offset Pb and Sn vacancies through Zn2+ ions incorporation, the oxalate group can strongly interact with undercoordinated metal ions to regulate film crystallization, delivering perovskite film with low defect density, high crystallinity, and superior electronic properties. Correspondingly, the resulting device delivers a champion efficiency of 14.1%, which presents the highest reported efficiency for bromine-rich inorganic PSCs thus far. More importantly, chemically reducing oxalate group can effectively suppress the notorious oxidation of Sn2+ , leading to significant enhancement on air stability.

Quantum Dot Interface-Mediated CsPbIBr2 Film Growth and Passivation for Efficient Carbon-Based Solar Cells.

CsPbIxBry-based all-inorganic perovskite materials are a potential candidate for stable semitransparent and tandem structured photovoltaic devices. However, poor film (morphological and crystalline) quality and interfacial recombination lead consequently to a decline in the photoelectric conversion performance of the applied solar cells. In this work, we incorporated PbS quantum dots (QDs) at the interface of electron transporting layer (ETL) SnO2 and perovskite to modulate the crystallization of CsPbIBr2 and the interfacial charge dynamics in carbon-based solar cells. The as-casted PbS QDs behave as seeds for lattice-matching the epitaxial growth of pinhole-free CsPbIBr2 films. The modified films with reduced defect density exhibit facilitated carrier transfer and suppressed charge recombination at the ETL/perovskite interface, contributing to an enhanced device efficiency from 7.00 to 9.09% and increased reproducibility and ambient stability. This strategic method of QD-assisted lattice-matched epitaxial growth is promising to prepare high-quality perovskite films for efficient perovskite solar cells.

Synchronization criteria for quaternion-valued coupled neural networks with impulses.

We consider the global exponential synchronization of a category of quaternion-valued coupled neural networks (QVCNNs) with impulses in this article. It makes up for the gap of coupled neural networks with impulses in quaternion. On account of the product of two quaternions cannot be exchanged under normal circumstances, for convenience, we isolate the QVCNN into four real-valued coupled neural networks (RVCNNs) which are converted into an augmented system by defining a new augmented vector. By leveraging a distinctive Lyapunov-Krasovskii function and some matrix inequalities, several sufficient conditions for the global exponential synchronization of the system are attained. Ultimately, two examples are used to prove the validity of the theories in this paper.

Investigate on plasma catalytic reaction of 4-nitrobenzenethiol on Ag@SiO2Core-Shell substrate via Surface-enhanced Raman scattering.

Surface-enhanced Raman scattering (SERS) is a promising technique to investigate the plasmon-driven catalytic reaction, in which the Raman signal originates from the electromagnetic (EM)enhancement mechanism and the chemical enhancement (CE) mechanism. Here, we designed and synthesized a novel SERS substrate based on SiO2 wrapped Ag nanoparticles (Ag@SiO2 core-shell nanoparticles substrate, Ag@SiO2 CSNS). Meanwhile, the SERS substrate based on Ag nanoparticles (Ag NS) also was prepared for comparison. Then, plasmon-driven catalytic reaction of 4-nitrobenzenethiol (4-NBT) to p,p'-dimercaptoazobenzene (DMAB) were systematically investigated on Ag and Ag@SiO2, respectively. The result revealed that, the Fermi level of Ag@SiO2 CSNS is lower than Ag NS, and the catalytic reaction greatly hindered by the Ag@SiO2 CSNS under the same excitation laser wavelength. With the same condition excitation laser, Raman signal enhancement effects are different when applying Ag NS and Ag@SiO2 CSNS, which could be attributed to that the inert SiO2 shell eliminates CE mechanism of the Raman signal. These results provide a simple strategy to figure out the mechanism of the catalytic reaction based on Surface-enhanced Raman scattering.