1,721,038 research outputs found
Host Matrix Materials for Luminescent Solar Concentrators: Recent Achievements and Forthcoming Challenges
Full text linkLuminescent solar concentrators (LSCs) have attracted increasing attention in the past few years as appealing solar energy technology for the seamless integration of photovoltaic (PV) systems into the built environment. Traditionally, research in this field has focused on two main aspects: the optimization of the device assembly, in the quest for more efficient architectures to maximize collection, transport, and conversion of photons into usable electrical energy; the development of novel, highly emissive luminescent species, to ensure broad light collection and efficient photon emission. Only recently, the attention has also been directed toward the selection and development of suitable host matrix/waveguide materials with appropriate optical properties, sufficient chemical compatibility with the guest luminescent species, good processability for easy device fabrication and prolonged durability in outdoor operation. In addition to consolidated polymeric systems based on polyacrylates or polycarbonates, in recent years different examples of alternative host matrix systems have been proposed, characterized by peculiar chemical, physical and optical characteristics specifically designed to meet the stringent requirements of the LSC technology. This mini-review will focus on recent developments in the design of new host matrix materials for LSC applications. An overview of the most recent examples of novel LSC host matrices will be provided here, mainly focusing on new polymers, polymer-based organic-inorganic hybrids and multifunctional organic systems. Finally, opportunities and challenges in the field will be considered in view of the effective exploitation of the LSC technology in real application scenarios
Polymeric materials for photon management in photovoltaics
No full textIn the field of photovoltaics, achieving high efficiency in both light absorption and light trapping simultaneously remains challenging. Photon management, which refers to the engineering of materials and device architectures to control the spatial or spectral distribution of optical energy, offers a number of promising approaches for the optimization of this tradeoff. Among these are antireflective structures with pronounced surface patterned profiles that reduce surface reflectivity, light trapping approaches but also spectral conversion concepts. With the continuous development of photovoltaic device architectures and designs, the engineering of novel photon management strategies and the availability of suitably tailored polymeric materials for such applications will contribute to enhanced device efficiencies as well as sustained long-term performance. In this review, we summarize the recent progress in the development and implementation of photon management strategies for different photovoltaic technologies specifically based on the use of polymeric materials, and we discuss their contribution to the field
Diels-Alder Macromolecular Networks in Recyclable, Repairable and Reprocessable Polymer Composites for the Circular Economy – A Review
Full text linkIn the expanding field of high-performance materials, polymer-based thermoset composites play an important role due to their favorably-high strength/weight ratio and their mechanical performance, thermal stability, and chemical resistance. However, their chemically-crosslinked nature hampers their re-processability and efficient recyclability, thus making them not compliant with the principles of the circular economy and of end-of-life valorization. Dynamic covalent polymers able to modify their network topology upon thermal stimulus can be considered valid alternatives to commonly used thermosets as they offer advantages in terms of recyclability and reusability, normally not achievable with conventional cross-linked systems. Within the broad field of dynamic polymers, thermally-triggered Diels-Alder based materials represent reliable platforms with enormous technological and industrial potential as repairable, reusable and recyclable matrices in composites given their chemical versatility, suitable mechanical performance and ease of production and processing. In this review, a comprehensive discussion of the most recent demonstrations of the reversibility, reprocessability and recyclablability of such systems is provided, in the context of their use as polymer matrices in composites. It is hoped that this work will stimulate further discussion and research in the area of reversible polymer composites with increased functionality and extended lifetime, in view of their application in future circular economy scenarios
Stimuli-responsive polymer nanocomposites: Reversibility as a tool for advanced manufacturing of functional devices
No full textOver the past decade, rapid developments and advancements in the electronic industry have led to a sharp increase in electronic waste (e-waste) disposed in landfills and not reusable. A wide and diversified range of advanced materials are present in e-waste. Among them, polymer nanocomposites represent a valuable example of high-added-value materials that can have however negative environmental consequences. Although thermoset polymer nanocomposites have demonstrated various beneficial properties such as high chemical resistance, and good mechanical strength, owing to their covalently crosslinked network, their potential damage could shorten the lifespan of electronic devices, increasing the amount of e-waste. To extend their service life, polymer matrices with self-healing abilities, and a good recovery of mechanical properties after healing have been developed. In this context, polymer matrices with dynamic covalent bonds activated by a thermal stimulus stand out as an attractive choice because they combine the re-processability of thermoplastics with the high mechanical performance of thermoset polymers. This chapter will discuss two emerging categories of polymer matrices with thermally reversible covalent bonds: Diels-Alder (DA)- and vitrimer-based systems. Within these two classes of dynamic polymer nanocomposites, the focus will be on the reaction mechanisms enabling self-healing, the types of nanofillers used, the recovery of mechanical and functional properties after damage, and the potential applications in devices and sensors. This work will therefore foster new studies and discussions in the field of repairable electronic and functional devices to prolong their lifetime and reduce their environmental impact
Fluoropolymeric luminescent downshifters for organic-dye-sensitized solar cells
No full textAs a feasible option for photovoltaic technology to meet the growing energy demand, dye-sensitized solar cells (DSSCs) have attracted much attention due to their low cost, ease of fabrication and good performance. In particular, metal-free organic dyes are currently under investigation because of their low cost and high molar extinction coefficient; thus, they are ideal sensitizer for large-scale applications. However, their absorption range is often narrow, so that an important portion of the solar spectrum is not absorbed. In this context, we think that luminescent materials, which are capable of converting a broad spectrum of light into photons of a particular wavelength, can be used to improve the light harvesting efficiency of the solar-cell-based energy conversion process. In this work, for the first time ever new crosslinked fluoropolymeric systems are employed as luminescent downshifters for organic-dye-sensitized solar cells. The effect of these parameters on the photovoltaic cells and the study of devices aging will be presente
Laboratory protocols for measuring and reporting the performance of luminescent solar concentrators
Full text linkLuminescent solar concentrators (LSCs) show great potential for both broadening the spectral response of photovoltaic devices and facilitating their deployment in urban environments. However, the recent success of LSCs has brought to light severe deficiencies in reporting protocols: direct comparison between lab-scale LSCs is not possible due to inconsistencies in the experimental measurements and reporting of device performance. Here, we make the case for treatment of LSCs as photonic devices rather than photovoltaic cells and identify best practice guidelines for the measurement and reporting of LSC performance
Polymers and photopolymers engineering to achieve unconventional properties in solar cells and smart windows
No full textPhotovoltaic (PV) technology has evolved rapidly in the past few decades and now encompasses a large variety of materials and device structures. A key aspect to be taken into account in any PV technology is the operational durability of these systems in outdoor conditions. In this context, the large compositional flexibility of polymeric materials as well as their proven easy processability may be of great help.
The first part of this contribution shows a series of photocurable fluoropolymeric systems that find application as multifunctional coatings for different solution-processable PV devices, including perovskite solar cells and photoelectrochromic windows. Aspects related to the chemical functionalization of the coating precursors will be addressed in view of the incorporation of multiple functionalities into the final coating material, such as high photochemical durability, luminescent down-shifting, UV-screening, high hydrophobicity and easy-cleanability. It will also be demonstrated that by synthetically tuning the functionality of the coating system, improved power conversion efficiency and unmatched long-term operational stability can be achieved on all PV systems investigated.
In the second part of this contribution, patterned “Fakir”-shaped super-hydrophobic polymeric architecture on the external sided of flexible solar cells are demonstrated to pave the way to floating PV devices. This represents and emerging trend in the PV scenario, with the ambitious aim to avoid not only the overheating of cells and water evaporation from water bodies in the driest areas, but also the installation of photovoltaic systems on land, thus reserving land use for agriculture or building
Luminescent Solar Concentrators for Photoelectrochemical Water Splitting
No full textSolar-driven electrolysis accomplished through photovoltaic (PV) devices is a major candidate for a long-term sustainable energy economy. However, the visually appealing integration of PV cells or panels into the built environment or in mobile applications is a fundamental requirement for this technology to expand and grow further. In this view, we investigated the exploitation of a luminescent solar concentrator (LSC) comprising multiple c-Si cells connected in series and parallel as a semitransparent device, capable of carrying out water electrolysis without an external bias. The optimized monolithic device comprises two series of four PV cells connected in parallel integrated into a planar LSC of 19.36 cm2 area, externally wired to an electrochemical cell having Pt and Ru-based electrodes as cathode and anode, respectively. LSC devices are evaluated under different illumination conditions, including diffuse light, to simulate urban or indoor environments. Maximum solar-to-hydrogen efficiency (STH) of 1.55% at 1 sun AM 1.5 G can be obtained with this setup, considering the whole front LSC area. These results represent the first demonstration of an electrolysis-based energy storage system exploiting LSC technology
Poly(vinylidenefluoride) polymers and copolymers as versatile hosts for luminescent solar concentrators: compositional tuning for enhanced performance
No full textNovel host matrices based on fluoropolymers blended with poly(methyl methacrylate) (PMMA) are presented in this work for application in efficient and photochemically stable thin-film luminescent solar concentrators (LSCs). These systems consist of blends of PMMA with three different partially fluorinated polymers in different proportions: polyvinylidenefluoride homopolymer, a copolymer of vinylidenefluoride and chloro-trifluoro-ethylene, and a terpolymer of vinylidenefluoride, hexafluoropropylene and hydroxyl-ethyl acetate. A detailed chemical, physical and structural characterization of the obtained materials allowed us to shed light on the structure-property relationships underlying the response of such blends as a LSC component, revealing the effect of the degree of crystallinity of the polymers on their functional characteristics. An optimization study of the optical and photovoltaic (PV) performance of these fluoropolymer-based LSC systems was carried out by investigating the effect of blend chemical composition, luminophore concentration and film thickness on LSC device output. LSCs featuring copolymer/PMMA blends as the host matrix were found to outperform their homopolymer- and terpolymer-based blend counterparts, attaining efficiencies comparable to those of reference PMMA-based LSC/PV assemblies. All optimized LSC systems were subjected to weathering tests for over 1000 h of continuous light exposure to evaluate the effect of the host matrix system on LSC performance decline and to correlate chemical composition with photochemical durability. It was found that all fluoropolymer/PMMA-based LSCs outperformed reference PMMA-based LSCs in terms of long-term operational lifetime. This work provides the first demonstration of thermoplastic fluoropolymer/PMMA blends for application as host matrices in efficient and stable LSCs and widens the scope of high-performance thermoplastic materials for the PV field
Highly Transparent and Colorless Self-Healing Polyacrylate Coatings Based on Diels–Alder Chemistry
Full text linkThe efficient integration of reversible polymer networks into acrylate-based polymeric materials is of peculiar interest for the development of coatings that combine high transparency with self-healing ability. In this work, reversible networks are obtained by reacting a series of linear copolymers of furfuryl methacrylate with aliphatic bismaleimides through Diels–Alder (DA) reaction between furan and maleimide moieties. Owing to dynamic crosslinking, the obtained coatings exhibit thermal reversibility, as determined by differential scanning calorimetry and dissolution experiments. Furthermore, upon heating over the retro-DA temperature, an excellent recovery of mechanically induced surface damages proves successful thermal remendability. Compared to previous reports on DA-based acrylate networks, the presented thermally responsive coatings exhibit outstanding transparency and absence of color, as a result of an accurate choice of suitable monomeric precursors. In addition, a pronounced hydrophobic behavior and excellent adhesive properties make the proposed material particularly suitable for optical applications
- …
