Dual Sub-Cells Modification Enables High-Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells

Monolithic perovskite/organic tandem solar cells (POTSCs) have attracted increasing attention owing to ability to overcome the Shockley–Queisser limit. However, compromised sub-cells performance limits the tandem device performance, and the power conversion efficiency (PCE) of POTSCs is still lower than their single-junction counterparts. Therefore, optimized sub-cells with minimal energy loss are desired for producing high-efficiency POTSCs. In this study, an ionic liquid, methylammonium acetate (MAAc), is used to modify wide-bandgap perovskite sub-cells (WPSCs), and bathocuproine (BCP) is used to modify small-bandgap organic solar cells. The Ac⁻ group of MAAc can effectively heal the Pb defects in the all-inorganic perovskite film, which enables a high PCE of 17.16% and an open-circuit voltage (V_oc) of 1.31 V for CsPbI_2.2Br_0.8-based WPSCs. Meanwhile, the BCP film, inserted at the ZnO/organic bulk-heterojunction (BHJ) interface, acts as a space layer to prevent direct contact between ZnO and the BHJ while passivating the surface defects of ZnO, thereby mitigating ZnO defect-induced efficiency loss. As a result, PM6:CH1007-based SOSCs exhibit a PCE of 15.46%. Integrating these modified sub-cells enable the fabrication of monolithic n–i–p structured POTSCs with a maximum PCE of 22.43% (21.42% certified), which is one of the highest efficiencies in such type of POTSCs.     

In Situ Fabrication of Metal–Organic Framework Thin Films with Enhanced Pervaporation Performance

The intrinsic porosity in the periodic structures of metal–organic frameworks (MOFs) endows them with a great potential for membrane separation. However, facile fabrication of crystalline MOF membranes has been challenging and limited to few materials for economic and environmental considerations. Herein, a continuous Zr-MOF thin film with a thickness of ≈180 nm has been fabricated via in situ recrystallization of MOF nanoparticles on the porous support under formic acid vapor. Owing to the inherent microporosity and the well-established hydrophilicity during membrane fabrication, the MOF thin films exhibit excellent pervaporation performance with separation factors of 2630, 501 and fluxes of 1.45, 1.41 kg m⁻² h⁻¹) for n-butanol dehydration and methanol/methyl tert-butyl ether (MeOH/MTBE) separation, respectively. The structural stability of the film has been further confirmed by its steady performance in the 10-day pervaporation test. This in situ recrystallization method induced by a trace amount of acid vapor with no extra ingredients opens a new avenue for the facile membrane fabrication of various MOF materials to feasibly realize their versatile potential as membrane materials.     

Vanadium Oxide Intercalated with Conductive Metal–Organic Frameworks with Dual Energy-Storage Mechanism for High Capacity and High-Rate Capability Zn Ion Storage

Vanadium oxides (VO_x) feature the potential for high-capacity Zn²⁺ storage, which are often preintercalated with inert ions or lattice water for accelerating Zn²⁺ migration kinetics. The inertness of these preintercalated species for Zn²⁺ storage and their incapability for conducting electrons, however, compromise the capacity and rate capability of VO_x. Herein, Ni-BTA, a 1D conductive metal–organic framework (c-MOF), is intercalated into the interlayer space of VO_x by coordinating organic ligands with preinserted Ni²⁺. The intercalated Ni-BTA improves the conductivity of VO_x by π–d conjugation, facilitates Zn²⁺ migration by enlarging its interlayer spacing, and stabilizes the crystal structure of VO_x as interlayer pillars, thus simultaneously enhancing the material's rate capability and cycling stability. Meanwhile, a dual reaction mechanism of Zn²⁺ storage, i.e., the redox of V⁵⁺/V³⁺ in VO_x and the rearrangement of chemical bonds (CN/C N) in Ni-BTA, collaboratively contributes to an enhanced capacity. Consequently, this Ni-BTA-intercalated VO_x material exhibits a high Zn²⁺ storage capacity of 464.2 mAh g⁻¹ at 0.2 A g⁻¹ and an excellent rate capability of 272.5 mAh g⁻¹ at 5 A g⁻¹. This work provides a general strategy for integrating c-MOFs with inorganic cathode materials to achieve high-capacity and high-rate performance.     

Good Thermal Stability,High Permittivity,Low Dielectric Loss and Chemical Compatibility with Silver Electrodes of Low-Fired BaTiO<Subscript>3</Subscript>–Bi(Cu<Subscript>0.75</Subscript>W<Subscript>0.25</Subscript>)O<Subscript>3</Subscript> Ceramics

(1 ? x)BaTiO₃–xBi(Cu_0.75W_0.25)O₃ [(1 ? x)BT–xBCW, 0 ≤ x ≤ 0.04] perovskite solid solutions ceramics of an X8R-type multilayer ceramic capacitor with a low sintering temperature (900°C) were synthesized by a conventional solid state reaction technique. Raman spectra and x-ray diffraction analysis demonstrated that a systematically structural evolution from a tetragonal phase to a pseudo-cubic phase appeared near 0.03 < x < 0.04. X-ray photoelectron analysis confirmed the existence of Cu⁺/Cu²⁺ mixed-valent structure in 0.96BT–0.04BCW ceramics. 0.96BT–0.04BCW ceramics sintered at 900°C showed excellent temperature stability of permittivity (Δε/ε _25°C ≤ ±15%) and retained good dielectric properties (relative permittivity ～1450 and dielectric loss ≤2%) over a wide temperature range from 25°C to 150°C at 1 MHz. Especially, 0.96BT–0.04BCW dielectrics have good compatibility with silver powders. Dielectric properties and electrode compatibility suggest that the developed materials can be used in low temperature co-fired multilayer capacitor applications.