In the quest for sustainable materials for quasi-solid-state (QS) electrolytes in aqueous dye-sensitized solar cells (DSSCs), novel bioderived polymeric membranes were prepared in this work by reaction of preoxidized kraft lignin with poly(ethylene glycol)diglycidylether (PEGDGE). The effect of the PEGDGE/lignin relative proportions on the characteristics of the obtained membranes was thoroughly investigated, and clear structure–property correlations were highlighted. In particular, the glass transition temperature of the materials was found to decrease by increasing the amount of PEGDGE in the formulation, indicating that polyethylene glycol chains act as flexible segments that increase the molecular mobility of the three-dimensional polymeric network. Concurrently, their swelling ability in liquid electrolyte was found to increase with the concentration of PEGDGE, which was also shown to influence the ionic transport efficiency within the membrane. The incorporation of these lignin-based cross-linked systems as QS electrolyte frameworks in aqueous DSSCs allowed the preparation of devices with excellent long-term stability under UV–vis light, which were found to be superior to benchmark QS-DSSCs incorporating state-of-the-art carboxymethylcellulose membranes. This study provides the first demonstration of lignin-based QS electrolytes for stable aqueous DSSCs, establishing a straightforward strategy to exploit the potential of lignin as a functional polymer precursor for the field of sustainable photovoltaic devices.

The organic solar cell initial burn-in loss is suppressed via the rational design of the polymer's chemical structure.

the development of approaches based on disulfide bond exchange, [3] alkoxyamine dissociation, [4] thiol-Michael reaction, [5] Alder-ene addition, [6] and bulky urea bonds, [7] the most widely reported systems are based on the well-established Diels-Alder (DA) cycloaddition. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] DA is a click-type addition reaction between a dienophile and a diene, typically a maleimide and a furan. The design of a polymer network where crosslinks are constituted by DA adducts would result in the ability to cleave the crosslinks at mildto-high temperature through a retro Diels-Alder process (r-DA), while enabling their reformation upon cooling through the direct DA reaction. Therefore, the r-DA/ DA sequence can be exploited to repair cracks or to remold the crosslinked material. [24] The concept, firstly described in a patent [25] and then in the milestone work of Wudl [26] has been exploited for the dynamic crosslinking of different polymer matrices like epoxies, [27,28] elastomers, [29,30] polyesters, [31,32] and polyketones. [33,34] A straightforward strategy to design DA crosslinked acrylates is based on the combination of linear copolymers of furfuryl methacrylates (FMAs) with difunctional maleimide linkers. [8][9][10]12,16,20] The reported systems are typically characterized by high healing efficiency. However, they lack in transparency and usually exhibit a yellow-to-orange color, predominantly due to the use of aromatic bismaleimide linkers. This feature factually forbids the utilization of DA-based acrylates for optical applications, where high levels of transmittance in the visible wavelength range are inevitably required.To bridge this gap, a straightforward strategy to prepare colorless and transparent thermoresponsive acrylates based on the DA chemistry is proposed in this work. Furan functional polyacrylates were synthetized via free radical polymerization of FMA with methacrylates bearing different aliphatic groups. Two aliphatic bismaleimides, with different chain length, were synthesized starting from the respective diamines. The obtained linear copolymers containing furan moieties were combined with the bismaleimides in solvent, and colorless, high-transmittance, crosslinked coatings were obtained. The thermal reversibility of the DA-coatings was assessed by means of differential scanning calorimetry (DSC) and solubility experiments. After assessing the self-healing ability of the acrylicbased polymeric materials, the effect of network structure (i.e.,

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framework, luminescent solar concentrators (LSCs) are a practical and versatile solution for the realization of buildingintegrated photovoltaics (BIPVs). [2] The idea behind the LSC concept is the replacement of large area PV modules with small solar cells positioned at the edge of a planar monolithic waveguide (e.g., a polymer-based thin-film deposited onto a glass substrate or a bulk plate) containing luminophore species. The luminophores absorb incident sunlight and emit photons which are redirected by total internal reflection toward the thin edges of the waveguide, where the PV elements convert the luminescent light into electricity. [3] Many different types of luminescent species (e.g., organic fluorophores, [4] perovskite nanocrystals, [5] carbon-dots, [6] and semiconductor quantum dots [7] ) have been extensively explored over the past decades in the attempt to achieve a combination of a broad absorption spectrum, a high light-harvesting efficiency, a high solid-state photoluminescence quantum yield (PLQY), and excellent photostability. [8] Nevertheless, the different luminophore-and waveguide-related loss pathways taking place in the LSC [8a,b,9a] still affect the optical performance of current systems and represent important obstacles to the sustainable commercialization of this technology.In this study, the design, fabrication, and characterization of semi-transparent large-area luminescent solar concentrators (LSCs) in thin-film configuration is reported, incorporating a novel organic luminophore (PFPBNT) emitter based on a π-conjugated core flanked by two naphthothiophene units obtained through a chemically sustainable synthetic approach. As found experimentally and validated through computational modeling, PFPBNT exhibits aggregation-induced emission (AIE) behavior, broad absorption in the UV-vis spectrum and significant Stokes shift (≈4632 cm -1 ), thereby making it an excellent candidate as luminophore in thin-film LSCs based on a poly(methyl methacrylate) (PMMA) matrix, where it is found to show good compatibility, homogeneous distribution, and excellent photostability. After extensive device optimization, PFPBNT/PMMA LSCs with suitable luminophore concentration (12.5 wt%) showed an internal photon efficiency of 17.3% at a geometrical gain of 6.25 under solar-simulated illumination. The size scalability of these systems was also evaluated by means of ray-tracing simulations on devices of up to 1 m 2 surface area. This work demonstrates semi-transparent large-area thin-film LSCs incorporating chemically sustainable AIEgen luminophores, thus opening the way to the development of synthetically affordable, efficient, and stable emitters for the photovoltaic field.

Luminescent solar concentrators (LSCs) represent a viable spectral conversion technology to maximize sunlight harvesting while promising to reduce the current gap for integration of solar cells into the built environment. In this work, novel highly emissive and photostable core-shell nanostructured luminescent species were synthesized and used in LSC devices. Such systems were obtained by entrapping Lumogen F Red 305 in silica-based shells by means of the sol-gel process using a combination of hydrophilic (tetraethyl orthosilicate) and hydrophobic (phenyl triethoxysilane) silica precursors. By tuning their relative proportions during the synthetic process, fine control over the characteristic dimensions and morphology of the obtained dye-doped core-shell nanoparticles could be achieved, leading to a maximum concentration of non-covalently entrapped fluorescent dye of ~1 wt.%. Optical characterization showed that the newly synthetized nanoparticles displayed markedly improved photoluminescence quantum yield in solid state (~ 95 %) with respect to the non-encapsulated dye (~ 2 %), as a result of an effective suppression of dye aggregation and fluorescence quenching phenomena. In addition, their excellent photostability under harsh UV light exposure was demonstrated, resulting from the protective action of the encapsulating hybrid silica-based shell, which can effectively limit photobleaching of the luminescent core. Their incorporation in thin-film LSCs led to a maximum internal photon efficiency as high as ~29%, thus providing evidence of their suitability as highly performing luminescent species with superior optical response and excellent photostability. Also, a maximum external photon efficiency as high as 2.12% was achieved. This work provides the first demonstration of silica-based encapsulation of Lumogen F Red 305 and of the application of silica-based core-shell nanoparticles in LSCs, thus paving the path to the development of a new class of highly efficient and stable nanostructured luminophores for the photovoltaic field.

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Luminescent solar concentrators (LSCs) are a promising solar energy technology for reducing architectural barriers to the integration of photovoltaic systems into the built environment. In this work, the first demonstration of thin-film LSCs based on a thermally reversible cross-linked host polymer is presented. This smart material is obtained via a dynamic-chemistry approach based on the Diels−Alder (DA) reaction between a furan-functionalized acrylic copolymer and an aliphatic bismaleimide to obtain optically clear, cross-linked systems capable of healing mechanical damage upon heat treatment. By carefully tuning the concentration of a perylene-based luminophore dopant, an optical efficiency as high as 4.9% can be achieved with this DA-based LSC. In addition, full recovery of device efficiency is demonstrated after complete thermal healing of mechanically induced surface damages as a result of the embedded DA functionality. The approach presented here paves the way to the development of highly efficient multifunctional thermoresponsive smart LSC systems.