Carbon‐based inorganic perovskite solar cells (C‐PSCs) have attracted intensive attention owing to their low cost and superior thermal stability. However, the bulk defects in perovskites and interfacial energy level mismatch seriously undermine their performance. To overcome these issues, a multifunctional dual‐interface engineering is proposed with a focus on low‐temperature CsPbI2Br C‐PSCs, where the potassium trifluoroacetate (KTFA) and the 4‐trifluorophenyl methylammonium bromide (CF3PMABr) are introduced beneath and on top of the perovskite layer, respectively. It is found that TFA‐ ions locate at the SnO2/CsPbI2Br interface, whereas a small amount of K+ ions diffuse into perovskite lattice to participate in nucleation and crystallization, resulting in more favored interfacial energy level alignment, improved film quality, passivated interfacial defects, released interfacial strain, as well as suppressed charge recombination and ion migration. Meanwhile, the CF3PMABr passivates I/Br vacancies and forms 2D perovskite capping layer to facilitate hole extraction at the CsPbI2Br/carbon interface. As a result, a remarkable power conversion efficiency (PCE) of 14.05% with an open‐circuit voltage of 1.273 V is achieved. To the best of the authors’ knowledge, it is currently the highest PCE reported for low‐temperature CsPbI2Br C‐PSCs. Furthermore, the nonencapsulated device exhibits improved moisture, thermal, and illumination stability in ambient air.

Fluorinated Interfaces for Efficient and Stable Low‐Temperature Carbon‐Based CsPbI2Br Perovskite Solar Cells

Piezoelectric materials and techniques for environmental pollution remediation.

Recent progress in improving strategies of inorganic electron transport layers for perovskite solar cells

The pesticide residues with low concentration are important to detect in food safety. Although a lot of methods, such as spectrophotometry, colorimetry and liquid chromatography, are used to detect pesticide residues, they often suffer from low efficiency and long detection time. Here, a hybrid Surface Enhanced Raman Scattering (SERS) substrate, namely, Au nanoparticle/copper-based graphene/arrayed cone cavities ([email protected]@Cu cone cavities), is fabricated for pesticide residues detection through sputtering Au nanoparticle and generating periodical cone cavity structures on the copper-based graphene surface. By actively controlling the interspace between adjacent cone cavities, both surface topographies and the number of graphene layers on the SERS substrate could be modulated, creating an effective control on the functional performance of the SERS substrate. Both sensitivity and reliability of the hybrid SERS substrate were evaluated by Raman Spectroscopy detection. The experimental results indicated that both 10−9 mol/L malachite green and 10−7 mol/L paraquat could be detected, respectively. Moreover, the detected Raman intensity of malachite green only dropped by 11.89% in a month and 29.8% in two months, respectively. The hotspot distribution was also characterized by 2-dimensional Raman mapping. The research finding is expected to provide a new insight in development of innovative SERS substrates. 

A study on a hybrid SERS substrates based on arrayed gold nanoparticle/graphene/Copper cone cavities fabricated by a conical tip indentation

High sensitivity, good signal repeatability, and facile fabrication of flexible surface enhanced Raman scattering (SERS) substrates are common pursuits of researchers for the detection of probe molecules in a complex environment. However, fragile adhesion between the noble-metal nanoparticles and substrate material, low selectivity, and complex fabrication process on a large scale limit SERS technology for wide-ranging applications. Herein, we propose a scalable and cost-effective strategy to a fabricate sensitive and mechanically stable flexible Ti3C2Tx MXene@graphene oxide/Au nanoclusters (MG/AuNCs) fiber SERS substrate from wet spinning and subsequent in situ reduction processes. The use of MG fiber provides good flexibility (114 MPa) and charge transfer enhancement (chemical mechanism, CM) for a SERS sensor and allows further in situ growth of AuNCs on its surface to build highly sensitive hot spots (electromagnetic mechanism, EM), promoting the durability and SERS performance of the substrate in complex environments. Therefore, the formed flexible MG/AuNCs-1 fiber exhibits a low detection limit of 1 × 10-11 M with a 2.01 × 109 enhancement factor (EFexp), signal repeatability (RSD = 9.80%), and time retention (remains 75% after 90 days of storage) for R6G molecules. Furthermore, the l-cysteine-modified MG/AuNCs-1 fiber realized the trace and selective detection of trinitrotoluene (TNT) molecules (0.1 μM) via Meisenheimer complex formation, even by sampling the TNT molecules at a fingerprint or sample bag. These findings fill the gap in the large-scale fabrication of high-performance 2D materials/precious-metal particle composite SERS substrates, with the expectation of pushing flexible SERS sensors toward wider applications.

Plasmonic Coupling of Au Nanoclusters on a Flexible MXene/Graphene Oxide Fiber for Ultrasensitive SERS Sensing.

The relatively weak Raman enhanced factors of semiconductor-based substrate limit its further application in surface-enhanced Raman scattering (SERS). Here, a kind of two-dimensional (2D) semimetal material, molybdenum carbide (Mo2C) film, is prepared via a chemical vapor deposition (CVD) method, and the origin of SERS is investigated for the first time. The detection limits of the prepared Mo2C films for crystal violet (CV) and rhodamine 6G (R6G) molecules are low at 10-6 M and 10-8 M, respectively. Our detailed theoretical analysis, based on density functional theory and the finite element method, demonstrates that the enhancement of the 2D Mo2C film is indeed CM in nature rather than the EM effects. Besides, the basic doping strategies are proposed to further optimize the SERS sensitivity of Mo2C for Fermi level regulation. We believe this work will provide a helpful guide for developing a highly sensitive semimetal SERS substrate.

The Origin of Mo2C Films for Surface-Enhanced Raman Scattering Analysis: Electromagnetic or Chemical Enhancement?

Annealing Free Tin Oxide Electron Transport Layers for Flexible Perovskite Solar Cells

To develop a universal and precise detection strategy that can be applied to water contaminants of various sizes, we designed a particle-in-MoS2 coated cavity structure of AAO/MoS2/Ag with a Raman internal standard. This modified particle-in-cavity structure not only successfully integrates both "surface hot spots" and "volume hot spots" via dressing and manipulating the cascaded optical-field mode inside the cavity but also introduces the chemical enhancement and internal standard attribute of MoS2. Because of its unique three-dimensional structure, AAO/MoS2/Ag accurately detects water contaminants of various sizes from ions to nanoplastics (<300 nm) for the first time. This work proposes a novel and universal surface-enhanced Raman scattering strategy for detecting multiple-size water contaminants and demonstrates the potential to build a security line in early warning systems for the prevention of water pollution.

Particle-in-Molybdenum Disulfide-Coated Cavity Structure with a Raman Internal Standard for Sensitive Raman Detection of Water Contaminants from Ions to <300 nm Nanoplastics.

Chao Zhang

Papers

The Origin of Mo2C Films for Surface-Enhanced Raman Scattering Analysis: Electromagnetic or Chemical Enhancement?

Annealing Free Tin Oxide Electron Transport Layers for Flexible Perovskite Solar Cells

Particle-in-Molybdenum Disulfide-Coated Cavity Structure with a Raman Internal Standard for Sensitive Raman Detection of Water Contaminants from Ions to <300 nm Nanoplastics.

Enhanced SERS and catalytic performance via piezoelectric and plasmonic coupling effects for organic pollutant molecule degradation

Plasmonic enhanced piezoelectric photocatalytic performance with PVDF@BT/MoS2/Au by strong piezoelectric functional particle doping