1,720,994 research outputs found
Shedding Light on Graphene Quantum Dots: Key Synthetic Strategies, Characterization Tools, and Cutting-Edge Applications
Full text linkDuring the last 20 years, the scientific community has shown growing interest towards carbonaceous nanomaterials due to their appealing mechanical, thermal, and optical features, depending on the specific nanoforms. Among these, graphene quantum dots (GQDs) recently emerged as one of the most promising nanomaterials due to their outstanding electrical properties, chemical stability, and intense and tunable photoluminescence, as it is witnessed by a booming number of reported applications, ranging from the biological field to the photovoltaic market. To date, a plethora of synthetic protocols have been investigated to modulate the portfolio of features that GQDs possess and to facilitate the use of these materials for target applications. Considering the number of publications and the rapid evolution of this flourishing field of research, this review aims at providing a broad overview of the most widely established synthetic protocols and offering a detailed review of some specific applications that are attracting researchers’ interest
Fast and Efficient Microwave-Assisted Synthesis of Perylenebisimides
No full textPerylene-3,4,9,10-tetracarboxylic acid bisimides have been widely studied as industrial pigments. Lately, these dyes have drawn considerable attention because of applications as photocatalysts and organic semi-conductors. Here, we report a novel method for fast and efficient synthesis of many different perylenebisimides, based on microwave-assisted reactions
Lichtaktivierte Sensoren zur empfindlichen Amindetektion
Full text linkUnsere neue, einfache und akkurate colorimetrische Methode basiert auf Diarylethenen (DAEs) zur schnellen Detektion einer großen Vielfalt primärer und sekundärer Amine. Die Sensoren bestehen aus aldehyd- oder ketonsubstituierten Diarylethenen, die selektiv ausgehend vom geschlossenen Isomer eine amininduzierte Entfärbungsreaktion eingehen. Somit können diese Sensoren zum gewünschten Zeitpunkt durch Lichteinstrahlung aktiviert werden und erlauben eine Empfindlichkeit der Amindetektion bis hinab zu 10-6M in Lösung. Zusätzlich ermöglicht die Immobilisierung auf Papier den Nachweis biogener Amine wie Cadaverin in der Gasphase oberhalb eines Grenzwerts von 12 ppbv innerhalb von 30 Sekunden
Artificial Biosystems by Printing Biology
Full text linkThe continuous progress of printing technologies over the past 20 years has fueled the development of a plethora of applications in materials sciences, flexible electronics, and biotechnologies. More recently, printing methodologies have started up to explore the world of Artificial Biology, offering new paradigms in the direct assembly of Artificial Biosystems (small condensates, compartments, networks, tissues, and organs) by mimicking the result of the evolution of living systems and also by redesigning natural biological systems, taking inspiration from them. This recent progress is reported in terms of a new field here defined as Printing Biology, resulting from the intersection between the field of printing and the bottom up Synthetic Biology. Printing Biology explores new approaches for the reconfigurable assembly of designed life-like or life-inspired structures. This work presents this emerging field, highlighting its main features, i.e., printing methodologies (from 2D to 3D), molecular ink properties, deposition mechanisms, and finally the applications and future challenges. Printing Biology is expected to show a growing impact on the development of biotechnology and life-inspired fabrication
Tackling Performance Challenges in Organic Photovoltaics: An Overview about Compatibilizers
Full text linkOrganic Photovoltaics (OPVs) based on Bulk Heterojunction (BHJ) blends are a mature technology. Having started their intensive development two decades ago, their low cost, processability and flexibility rapidly funneled the interest of the scientific community, searching for new solutions to expand solar photovoltaics market and promote sustainable development. However, their robust implementation is hampered by some issues, concerning the choice of the donor/acceptor materials, the device thermal/photo-stability, and, last but not least, their morphology. Indeed, the morphological profile of BHJs has a strong impact over charge generation, collection, and recombination processes; control over nano/microstructural morphology would be desirable, aiming at finely tuning the device performance and overcoming those previously mentioned critical issues. The employ of compatibilizers has emerged as a promising, economically sustainable, and widely applicable approach for the donor/acceptor interface (D/A-I) optimization. Thus, improvements in the global performance of the devices can be achieved without making use of more complex architectures. Even though several materials have been deeply documented and reported as effective compatibilizing agents, scientific reports are quite fragmentary. Here we would like to offer a panoramic overview of the literature on compatibilizers, focusing on the progression documented in the last decade
Semitransparent Perovskite Solar Cells for Building Integration and Tandem Photovoltaics: Design Strategies and Challenges
Full text linkOver the past decade, halide perovskite systems have captured widespread attention among researchers since their exceptional photovoltaic (PV) performance was disclosed. The unique combination of optoelectronic properties and solution processability shown by these materials has enabled perovskite solar cells (PSCs) to reach efficiencies higher than 25% at low fabrication costs. Moreover, PSCs display enormous potential for modern unconventional PV applications, since they can be made lightweight, semitransparent (ST), and/or flexible by means of appropriate design strategies. In particular, by enabling transparency and high efficiency simultaneously, ST-PSCs hold great promise for future versatile utilization in the context of building-integrated PVs (BIPVs) or as top cells to be coupled with conventional lower-bandgap bottom cells in tandem PV devices. The present Review wants to provide a detailed overview of latest research about ST-PSCs for BIPVs and tandems, by critically reporting on the most updated and effective design strategies in view of these two possible future applications. The differences and similarities between the available approaches are punctually highlighted, emphasizing the importance of a rigorous application-orientated ST-PSC design. Last but not least, the main challenges and issues about device design, operation, and stability that need to be addressed before commercialization are thoroughly scanned
Boosting the Performance of One-Step Solution-Processed Perovskite Solar Cells Using a Natural Monoterpene Alcohol as a Green Solvent Additive
Full text linkThe perovskite film is the core of a perovskite solar cell (PSC), and its quality is crucial for the performance of such devices. The morphology, crystallinity, and surface coverage of the perovskite layer greatly affect the power conversion efficiency (PCE), hysteresis, and long-term stability of PSCs. The incorporation of appropriate solvent additives in the perovskite precursor solution is an effective strategy to control the film morphology and reduce the defects and grain boundaries. However, the commonly used solvent additives are environmentally harmful and highly toxic. In this work, α-terpineol (a nontoxic, eco-friendly, and low-cost monoterpene alcohol) is employed for the first time as an alternative green solvent additive to improve the quality of one-step solution-processed CH3NH3PbI3–xClx films and to restrain nonradiative recombination in the corresponding devices. An in-depth investigation of the physicochemical effects induced by such a high-boiling-point, polar protic solvent when incorporated into a conventional perovskite solvent system is provided. The collected data demonstrate that the addition of a precise amount of α-terpineol can generate uniform and highly crystalline perovskite films with improved photovoltaic performances. Through this approach, the PCE of planar n–i–p PSCs is boosted up to 17.5% (against 16.1% of the top control device) with reduced hysteresis and enhanced ambient stability
Unravelling Radicals Reactivity Towards Carbon Nanotubes Manipulation/Functionalization
Full text linkCarbon Nanotubes (CNTs) chemistry is under constant evolution, as a consequence of the deep interest
of the scientific community in finding new applications for these versatile materials. New and old synthetic protocols
are used for improving the control of the functionalization degree of the final materials and for offering to scientists
the possibility to fine-tune their final properties. In this Review, we focus the attention on radical reactions,
a class of protocols characterized by small number of steps, different degrees of functionalization and enhanced
solubility of the final modified CNTs, in the desired environment. The most well-known protocols are analysed
providing some relevant examples appeared in the literature in the last years, monitoring the new application fields
and giving insights into their mechanism in order to explain why these protocols are considered standard procedures for a wide number of
scientific groups
Efficient microwave-assisted synthesis of PCBM methanofullerenes (C60 and C70)
No full textPCBM is a fullerene derivative (phenyl-C61-butyric acid methyl ester) considered to be one of the best n-type organic semiconductors and plays a relevant role in organic photovoltaic solar cells. Much effort has been devoted to the optimization of the synthesis of PCBM derivatives. In this paper, PC61BM and PC71BM fullerene mono-adducts but also PCBM-like derivatives are successfully prepared by a one-step cyclopropanation reaction under microwave irradiation. The products are collected in good yields in short time, during which isomerization of the open [5,6] to the closed [6,6] form takes place in situ. In addition, with the use of two cycles of irradiation, a series of mixtures of bis-adduct PCBM-like derivatives were also obtained in good yields
Blue-light-driven photoactivity of L-cysteine-modified graphene quantum dots and their antibacterial effects
No full textThe widespread abuse of traditional antibiotics has led to a global rise in antibiotic-resistant bacteria, which give in return unprecedented health risks. Therefore, there is a large and urgent need for the development of new, smart antibacterial agents able to efficiently kill or inhibit bacterial growth. In this study, we investigated the antibacterial activity of S, N-doped Graphene Quantum Dots (GQDs) as a light-triggered antibacterial agent. Gamma irradiation was employed as a tool to achieve one-step modification of GQDs in the presence of L-cysteine amino acid as a source of heteroatoms. X-ray Photoelectron Spectroscopy (XPS), nuclear magnetic
resonance (NMR), and zeta potential measurements provided the necessary data to clarify the structure of modified dots and verify the introduction of both S- and N-atoms in GQDs structure, but also severe changes in the aromatic, sp2 domains. Namely, γ-irradiation caused a bonding of S atoms in 1.14 at.% mainly as thiol groups, and N in 1.81 at.% as amino groups, but sp2 contribution in GQD structure was lowered from 63.00 to 4.86 at.%, as measured in dots irradiated at a dose of 200 kGy. Fluorescence quenching measurements showed that L-cysteine-modified dots are able to bind to human serum albumin. The antibacterial activity of GQDs
combined with 1 and 6 h of blue light (470 nm) irradiation was tested against 8 bacterial strains. GQD-cys-25 sample provided the best results, with minimum inhibitory concentration (MIC) as low as 125 μg/mL against S. aureus, E. faecalis, and E. coli after only 1 h of blue light exposure
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