Incorporating a third element in the active layer of organic photovoltaic (OPV) devices is a promising strategy towards improving the efficiency and stability of this technology while maintaining ...relatively low costs. While ternary organic solar cells (TOSCs) have been widely studied during the last decade, there has been a meteoric rise in TOSC research after a breakthrough efficiency of 14.1% was reported in 2017. Such values of efficiency make TOSC a promising third-generation solar technology, prompting worldwide research efforts into the inclusion of a third element for high-performance TOSCs. These efforts have further boosted their efficiency, which is currently approaching 19%, and improved the stability of OPVs. This review discusses the role of the third component in improving efficiency and stability, emphasizing the period after 2016, which witnessed huge increases in efficiency and the boom that ensued. Since their introduction in 2008 for applications in photovoltaics and optoelectronics, colloidal quantum dot solar cells (CQDSCs), among other third-generation technologies, have recently experienced a level of success comparable to TOSCs. Finally, we compare the performance of TOSCs to CQDSCs, a complementary third-generation solar technology.
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•Third element incorporation in OPVs is rapidly becoming a promising route for improvement in device performance.•Ternary organic solar cells (TOSCs) allow for the synthesis or choice of potentially novel low-cost materials.•The third component increases TOSCs’ absorption intensity and/or range among other parameters, leading to high efficiency.•TOSCs are explored for potential enhancement in stability in OPVs.
Silk fibroin-derived polypeptides (FDPs) are polypeptides resulting from the enzymatic separation of the hydrophobic crystalline (Cp) and hydrophilic electronegative amorphous (Cs) components of silk ...fibroin (SF). The role of these polypeptides in promoting the nucleation of hydroxyapatite (HA) has been previously investigated, yet is still not fully understood. Here we study the potential of HA mineralization via FDPs incorporated at 1:10, 1:2 and 1:1 in a plastically compressed (PC) and dense collagen (DC) scaffold. Scaffolds were immersed in simulated body fluid (SBF) at physiological conditions (pH = 7.4, 37°C) to promote biomineralization. The effect of Cs and Cp to promote HA nucleation was investigated at different time points, and compared to pure DC scaffolds. Characterization of Cs and Cp fragments using Liquid Chromatography-Mass Spectrometry (LCMS) showed little difference in the amino acid composition of the FDPs. Results obtained in vitro using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) X-Ray Diffraction (XRD) and mass analysis showed little difference between scaffolds that incorporated Cs, Cp, and DC hydrogels. These results demonstrated that silk FDPs incorporation are not yet suitable to promote HA nucleation in vivo without further refining the collagen-FDP system.
Ligand-free Ru nanoclusters supported on carbon black have been synthesized in situ for the first time from the reduction of RuCl3 by ammonia-borane concomitantly with its hydrolysis process at room ...temperature, and their catalytic activity has been investigated. Well dispersed Ru nanoclusters (∼1.7 nm) are stabilized and immobilized by carbon black. Due to the small size and the absence of ligands on the surface, the Ru catalysts exhibit high catalytic activity, which is partly retained after 5 reaction cycles. A kinetic study shows that the catalytic hydrolysis of ammonia-borane is first order with respect to Ru catalyst concentration; the turnover frequency is 429.5 mol H2 min−1 mol−1 Ru. The activation energy for the hydrolysis of ammonia-borane in the presence of Ru/C catalysts has been measured to be 34.81 ± 0.12 kJ mol−1, which is smaller than most of the values reported for other catalysts, including those based on Ru, for the same reaction.
▶ Ru nanoclusters on carbon black were in situ synthesized. ▶ Such synthesized Ru nanoclusters were used for hydrolysis of ammonia borane. ▶ These ligand-free nanoclusters don't need further treatment before catalysis. ▶ They exhibit high catalytic activity, low activation energy, and fair stability.
Core–shell quantum dots serve as self‐calibrating, ultrasensitive, multiparametric, near‐infrared, and biocompatible temperature sensors. They allow temperature measurement with nanometer accuracy in ...the range 150–373 K, the broadest ever recorded for a nanothermometer, with sensitivities among the highest ever reported, which makes them essentially unique in the panorama of biocompatible nanothermometers with potential for in vivo biological thermal imaging and/or thermoablative therapy.
Solar energy conversion using semiconductors to fabricate photovoltaic devices relies on efficient light absorption, charge separation of electron–hole pair carriers or excitons, and fast transport ...and charge extraction to counter recombination processes. Ferroelectric materials are able to host a permanent electrical polarization which provides control over electrical field distribution in bulk and interfacial regions. In this review, we provide a critical overview of the physical principles and mechanisms of solar energy conversion using ferroelectric semiconductors and contact layers, as well as the main achievements reported so far. In a ferroelectric semiconductor film with ideal contacts, the polarization charge would be totally screened by the metal layers and no charge collection field would exist. However, real materials show a depolarization field, smooth termination of polarization, and interfacial energy barriers that do provide the control of interface and bulk electric field by switchable spontaneous polarization. We explore different phenomena as the polarization-modulated Schottky-like barriers at metal/ferroelectric interfaces, depolarization fields, vacancy migration, and the switchable rectifying behavior of ferroelectric thin films. Using a basic physical model of a solar cell, our analysis provides a general picture of the influence of ferroelectric effects on the actual power conversion efficiency of the solar cell device, and we are able to assess whether these effects or their combinations are beneficial or counterproductive. We describe in detail the bulk photovoltaic effect and the contact layers that modify the built-in field and the charge injection and separation in bulk heterojunction organic cells as well as in photocatalytic and water splitting devices. We also review the dominant families of ferroelectric materials that have been most extensively investigated and have provided the best photovoltaic performance.
Chemical reactions that convert sp
to sp
hybridization have been demonstrated to be a fascinating yet challenging route to functionalize graphene. So far it has not been possible to precisely control ...the reaction sites nor their lateral order at the atomic/molecular scale. The application prospects have been limited for reactions that require long soaking, heating, electric pulses or probe-tip press. Here we demonstrate a spatially selective photocycloaddition reaction of a two-dimensional molecular network with defect-free basal plane of single-layer graphene. Directly visualized at the submolecular level, the cycloaddition is triggered by ultraviolet irradiation in ultrahigh vacuum, requiring no aid of the graphene Moiré pattern. The reaction involves both 2+2 and 2+4 cycloadditions, with the reaction sites aligned into a two-dimensional extended and well-ordered array, inducing a bandgap for the reacted graphene layer. This work provides a solid base for designing and engineering graphene-based optoelectronic and microelectronic devices.
Photocatalysis offers a practical solution to the ever increasing energy and environmental issues by using a semiconductor to harvest freely available sunlight. Photoactive organic semiconductor ...nanocrystals (OSNs) are promising photocatalysts due to their structure and function which are easily tunable by molecular design. Extensive studies have yielded significant progress on OSNs in terms of photoresponse, charge carrier mobility, as well as photoconversion efficiency. This review provides a comprehensive discussion of the emerging crystal and interface engineering strategies used in optimizing structure/property of OSNs. The basic mechanisms involved in organic photocatalysis are discussed, for a better understanding of its dependence on the molecular and supramolecular structures. Then, the intermolecular interactions in molecular packing and the kinetic and thermodynamic control over the crystal growth process are summarized, with the aim of tuning the optical and electrical properties. Band energy alignment, charge carrier dynamics, and charge transfer are discussed in different heterostructures. In each case, structure/property relationships and how to tune them are emphasized. Finally, challenges and opportunities for the practical use of the organic photocatalysts are discussed.
Precise control of the structure/property in photocatalytic organic nanocrystals is still an unresolved challenge. Relevant molecular crystal engineering strategies are reviewed by discussing the interplay of different intermolecular interactions and the kinetic and thermodynamic considerations to attain good structure/property control. To fulfill all the property requirements, interface engineering strategies are also used to design high‐efficiency and stable organic photoconversion systems.
All-solid-state lithium batteries (ASSLBs) are undoubtedly among the most promising technologies to replace conventional lithium-ion batteries. Their key component is a thin solid-state electrolyte, ...which is safer than its flammable liquid counterpart and enables the use of metallic lithium, thus ensuring high energy densities (over 500 W h kg−1). Several solid electrolytes are currently being investigated, such as NASICON-like materials, perovskites, and garnets. Typical techniques used to synthesize most such electrolytes still involve prolonged high-temperature calcination and sintering steps. An alternative approach is to couple electrospinning with the well-known sol–gel method to lower the temperatures and synthesis times and simultaneously exploit the benefits of using anisotropic nanostructured materials. In this review, we discuss advances in the synthesis of ceramic nanofibrous materials having high ionic conductivity and present our perspective regarding their potential application as electrolytes in ASSLBs.
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•Coupling electrospinning with sol-gel to synthesize ceramic nanofibrous materials.•1D ceramic materials to improve the performance of solid state electrolytes for lithium batteries.•Future challenges and opportunities for highly ion-conductive ceramic nanofibers.
Core-shell structured Ni@Ru bimetallic nanoparticles are demonstrated as a bifunctional nanoplatform system for the hydrolysis reaction of ammonia-borane and also for magnetic separation.
Lanthanide-doped upconverting nanoparticles (UCNPs), which convert near-infrared (NIR) light to higher energy light have been intensively studied for theranostic applications. Here, we developed a ...hybrid core/shell nanocomposite with multifunctional properties using a multistep strategy consisting of a gold nanorod (GNR) core with an upconverting NaYF4:Er3+, Yb3+ shell (GNR@NaYF4:Er3+, Yb3+). To use a single excitation beam, the GNR plasmon was tuned to ∼650 nm, which is resonant with the upconverted red Er3+ emission emanating from the 4F9/2 excited state. Thus, under laser irradiation at 980 nm, the intensity ratio of the upconverted green emission (arising from the 2H11/2 and 4S3/2 excited states of Er3+) showed a remarkable thermal sensitivity, which was used to calculate the temperature change due to rapid heat conversion from the GNR core. The red upconversion emission of the GNR@NaYF4:Er3+, Yb3+ core/shell nanocomposite decreased compared with the NaYF4:Er3+, Yb3+ nanoshell structure (without a GNR core), which indicates that energy transfer from NaYF4:Er3+, Yb3+ to the GNR takes place, subsequently causing a photothermal effect. The anticancer drug, doxorubicin, was loaded into the GNR@NaYF4:Er3+, Yb3+ nanocomposites and the drug release profile was evaluated. In particular, the release of doxorubicin was significantly enhanced at lower pH and higher temperature caused by the photothermal effect. This multifunctional nanocomposite, which is suitable for local heating and controlled drug release, shows strong potential for use in cancer therapy.
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