It is well-known nowadays that the usage of conventional opaque photovoltaics in agricultural practices has negative effects on crops growth, mainly due to the shading effect they cause. On the other hand, most of the emerging semi-transparent solar cells do not demonstrate the appropriate optical characteristics and scalability to attain their viable integration in agriculture, undermining their commercialization. This study deals with the development of wavelength-selective semi-transparent dye-sensitized solar cells (DSSCs) using the scalable slot-die deposition method. These devices are designed to provide high transparency in the photosynthetically active radiation (PAR) region and effectively exploit the near-ultraviolet to blue-visible spectrum for power production, simultaneously protecting cultivations from harmful short-wavelength irradiation. To this aim, a new quinoline-based dye and a highly transparent iodine-free electrolyte were employed in DSSCs, giving an external quantum efficiency of 70% for wavelengths up to 500 nm and a PAR transmittance on the level of 50% (55% crop growth factor). Additionally, the light-to-electricity conversion efficiency of these devices is high for both front- and rear-side illumination under all-weather irradiation conditions (up to 94% bifaciality factor). Finally, two new figures-of-merit (greenhouse compatibility factor, agrivoltaic performance factor) are introduced to quantify the balance of photovoltaic performance and agronomic functionality.

Incorporating perylene diimide (PDI) into polymeric structures is a promising strategy to suppress its aggregation-caused quenching. However, achieving this while maintaining desirable material properties remains a challenge. This work aims to the realization of polymeric fluorophores via the incorporation of perylene diimide (PDI) derivatives onto the main chain of poly(arylene ethers) containing different organic chromophores as comonomers. The potentiality of PDI-based polymers for the emitting layer of organic light-emitting diodes is studied herein. Different percentages of the perylene diimide derivative were used to ensure emission from the PDI core components, while minimizing their strong pi-pi stacking tendency and thus their emission quenching. Two different chromophore combinations were employed with the potential to obtain white light-emitting copolymers. The first involved the use of two fluorophores, namely, a diacetoxystyrylcarbazole derivative along with the perylene moiety. The latter involved the use of a diacetoxystyryl anthracene moiety to facilitate better energy transfer to the perylene moiety. In both cases, the emission of the perylene core component was observed, providing a synthetic strategy to suppress the aggregation tendency of PDI.

Organic photovoltaics (OPVs) present a promising and potentially more sustainable avenue to solar energy utilization compared to crystalline solar cells, by using printable materials with minimum energy requirements. However, potential environmental impact reductions need to be evaluated throughout their life cycle, with many existing studies relying on legacy bibliographic data that are not representative of state-of-the-art advancements from a material and device engineering perspective. This study conducts a cradle-to-gate life cycle assessment of the synthesis pathways of highly efficient polymeric donors (PCDTBT, PTQ10), used in the active layer of OPVs. We provide new inventory data that can be incorporated in future LCA studies to enable comparative evaluations of this technology to traditional Si-based solar cells. PCDTBT synthesis revealed a GWP100 of 28.6 kg CO2-eq per kg, which is 15 times higher than P3HT. However, in a complete device, the PCDTBT cell has an 8.7% lower impact per Wp due to higher efficiency. By relying on lab-scale primary data, this study provides insights into the trade-offs involved in material design and process optimization, contributing to the identification of sustainable synthetic pathways for OPV materials. These findings demonstrate the importance of life cycle assessment in the early stages of OPV device development to inform environmentally friendly design and production at scale.

Polymers containing π-conjugated segments are a diverse group of large molecules with semiconducting and emissive properties, with strong potential for use as active layers in Organic Light-Emitting Diodes (OLEDs). Stable blue-emitting materials, which are utilized as emissive layers in solution-processed OLED devices, are essential for their commercialization. Achieving balanced charge injection is challenging due to the wide bandgap between the HOMO and LUMO energy levels. This study examines the optical and photophysical characteristics of blue-emitting polymers to contribute to the understanding of the fundamental mechanisms of color purity and its stability during the operation of OLED devices. The investigated materials are a novel synthesized lab scale polymer, namely poly[(2,7-di(p-acetoxystyryl)-9-(2-ethylhexyl)-9H-carbazole-4,4′-diphenylsulfone)-co-poly(2,6-diphenylpyrydine-4,4′-diphenylsulfone] (CzCop), as well as three commercially supplied materials, namely Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), poly[9,9-bis(2′-ethylhexyl) fluorene-2,7-diyl] (PBEHF), and poly (9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole) (F6PC). The materials were compared to evaluate their properties using Spectroscopic Ellipsometry, Photoluminescence, and Atomic Force Microscopy (AFM). Additionally, the electrical characteristics of the OLED devices were investigated, as well as the stability of the electroluminescence emission spectrum during the device’s operation. Finally, the determined optical properties, combined with their photo- and electro-emission characteristics, provided significant insights into the color stability and selectivity of each material.

Organometallic ruthenium complexes with p-cymene = 1-methyl-4-(1-methylethyl)-benzene and N^N = bidentate polypyridyl ligands constitute interesting candidates with biological and catalytic properties. Towards this aim, we have synthesized four ruthenium(II)–arene complexes of the type [Ru(η6-p-cymene)(N^N)Cl][X] (N^N = Br-Qpy = 6-bromo-4-phenyl-2-pyridin-2-yl-quinoline, X = Cl− (1a); PF6− (1b); N^N = OH-Ph-Qpy = 4-(4-phenyl-2-(pyridin-2-yl)quinolin-6-yl)phenol, X = Cl− (2a); PF6− (2b)). This is the first report of ruthenium(II) p-cymene complexes incorporating substituted pyridine–quinoline ligands, with –Br and –C6H4OH groups in the 6-position of quinoline. We also refer to the cytotoxicity of the ligands and their possible effect of modulating the activity of the ruthenium(II) complexes. These were characterized by a combination of spectroscopic methods (ATR-IR, UV–Vis, multinuclear NMR), elemental analysis, and conductivity measurements. The solid-state structure of 2b, determined by single-crystal X-ray diffraction, reveals a three-legged piano-stool geometry. The in vitro cytotoxic activities of the new complexes were evaluated in HEK293T (human embryonic kidney cells) and in HeLa cells (cervical cancer cells), via the MTT assay. Poor in vitro anticancer activities were observed for the HeLa cancer cell line, with 2a being the most potent (IC50 = 75 μΜ). The cytotoxicity of Br-Qpy in HEK293T is comparable to that of cisplatin. Both complexes 1a and 1b successfully catalyze the transfer hydrogenation of benzophenone to benzhydrol by 2-propanol at 82 °C. The catalytic performance of 1a in the ratio of S:Cat:B = 400:1:40 (S = substrate, Cat = catalyst, B = base = KOiPr) leads to a conversion of 94%, within 3 h of reaction. Presumably, catalytic transformation takes place via ruthenium(II) hydride species being the active catalyst.

In this study, fully aromatic polyether sulfones were developed, bearing blue, yellow, and orange–red π-conjugated semiconducting units. Carbazole-, anthracene-, and benzothiadiazole-based fluorophores are copolymerized with a diphenylsulfone moiety. A diphenylpyridine comonomer was additionally utilized, acting as both a solubilizing unit and a weak blue fluorescent group. Using this rationale, fluorescent polyarylethers with high molecular weights, up to 70 kDa, were developed, showing film formation ability and high thermal stability, while preserving excellent solubility in common organic, nonvolatile, and nonchlorinated solvents. Fine-tuning of the emission color was achieved through subtle changes of the comonomers’ type and ratio. Single-chromophore-bearing copolymers emitted in the blue or the yellow region of the visible spectrum, while the dual-chromophore-bearing terpolymers emitted throughout the visible spectrum, resulting in white light emission. Solutions of 20 wt% in polar aprotic solvents at ambient conditions allowed the deposition of fluorescent copolyethers and printing from non-chlorinated solvents. All polyethers were evaluated for their structural and optoelectronic properties, and selected copolymers were successfully used in the emitting layer (EML) of organic light-emitting diode (OLED) devices, using either rigid or flexible substrates. Remarkable color stability was displayed in all cases for up to 15 V of bias voltage. The Commission Internationale de L’Eclairage (CIE) of the fabricated devices is located in the blue (0.16, 0.16), yellow (0.44, 0.50), or white region of the visible spectrum (0.33, 0.38) with minimal changes according to the ratio of the comonomers. The versatile methodology toward semiconducting polyethersulfones for polymer light-emitting diodes (PLEDs) developed herein led to the scaled-up production of luminescent polymers of up to 25 g of high-molecular-weight single batches, demonstrating the effectiveness of this approach as a straightforward tool to facilitate the synthesis of flexible and printable EMLs for large-area PLED coverage.

Extensive research has been dedicated to the solution-processable white organic light-emitting diodes (WOLEDs), which can potentially influence future solid-state lighting and full-color flat-panel displays. The proposed strategy based on WOLEDs involves blending two or more emitting polymers or copolymerizing two or more emitting chromophores with different doping concentrations to produce white light emission from a single layer. Toward this direction, the development of blends was conducted using commercial blue poly(9,9-di-n-octylfluorenyl2,7-diyl) (PFO), green poly(9,9-dioctylfluorenealt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, whereas the synthesized copolymers were based on different chromophores, namely distyryllanthracene, distyrylcarbazole, and distyrylbenzothiadiazole, as yellow, blue, and orange–red emitters, respectively. A comparative study between the two approaches was carried out to examine the main challenge for these doping systems, which is ensuring the proper balance of emissions from all the units to span the entire visible range. The emission characteristics of fabricated WOLEDs will be explored in terms of controlling the emission from each emitter, which depends on two possible mechanisms: energy transfer and carrier trapping. The aim of this work is to achieve pure white emission through the color mixing from different emitters based on different doping concentrations, as well as color stability during the device operation. According to these aspects, the WOLED devices based on the copolymers of two chromophores exhibit the most encouraging results regarding white color emission coordinates (0.28, 0.31) with a CRI value of 82.

This study outlines a method for the epoxidation of poly-beta-myrcene, a biopolymer that can be easily extracted from the natural resin of the Chios Mastic tree (Pistacia lentiscus L.). The resulting epoxidation products are self-curing, and have a nearly 100% green carbon content. These Mastic Epoxide products (MASTEP) have the potential to be useful thermosetting resins. One specific product (MASTEP A), was used as an adhesive to create Single Lap Joints, which were then subjected to tensile shear stress tests. MASTEP A was found to be 25%-83% stronger than three commonly used conventional or "semi-green" epoxy adhesives. Another specific product (MASTEP B), was found able to be thermally converted into a semi-crystalline form. In order to clarify the 3D chemical structure of MASTEP, IR, and DSC investigations were conducted. The entire production process was designed to be environmentally friendly. The results of this research represent a significant advancement in the development of environmentally friendly epoxies and pave the way to a wide range of potential further research.

Pyridine‐containing polyethersulfone films are being studied extensively as they are considered promising types of polymer electrolyte membranes to be used in high‐temperature fuel cell (HT‐PEMFC) applications. In this study, modified polyethersulfone films doped with phosphoric acid were bombarded by a 3 keV argon ion beam resulting in a different chemical environment at the end of the sputtering process. X ray Photoelectron spectroscopy (XPS) was employed to analyze the changes that occurred due to the exposure to the beam, confirming that distinct species appeared and indicating that reactions between the acid and the film occurred. These changes cause the formation of new phosphine‐based structures and point out the impact of ions as a crucial factor in the degradation of doped polyethersulfone films.

A systematic study of the influence of the chemical substitution pattern of semiconducting polymers carrying side chain perylene diimide (PDI) groups is presented. Semiconducting polymers based on perflurophenyl quinoline (5FQ) were modified via a readily accessible nucleophilic substitution reaction. The perfluorophenyl group was studied as an electron-withdrawing reactive functionality on semiconducting polymers that can undergo fast nucleophilic aromatic substitution. A PDI molecule, functionalized with one phenol group on the bay area, was used for the substitution of the fluorine atom at the para position in 6-vinylphenyl-(2-perfluorophenyl)-4-phenyl quinoline. The final product was polymerized under free radical polymerization providing polymers of 5FQ incorporated with PDI side groups. Alternatively, the post-polymerization modification of the fluorine atoms at the para position of the 5FQ homopolymer with the PhOH-di-EH-PDI was also successfully tested. In this case, the PDI units were partially introduced to the perflurophenyl quinoline moieties of the homopolymer. The para-fluoro aromatic nucleophilic substitution reaction was confirmed and estimated via 1H and 19F NMR spectroscopies. The two different polymer architectures, namely, fully or partially modified with PDI units, were studied in terms of their optical and electrochemical properties, while their morphology was evaluated using TEM analysis, revealing polymers of tailor-made optoelectronic and morphological properties. This work provides a novel molecule-designing method for semiconducting materials of controlled properties.

The synthesis and characterization of water-soluble copolymers containing N,N-dimethylacrylamide (DMAM) and a vinylic monomer containing an Iridium(III), Ir(III), complex substituted with the quinoline-based unit 2-(pyridin-2-ylo)-6-styrene-4-phenylquinoline (VQPy) as ligand are reported. These copolymers were prepared through pre- or post-polymerization complexation of Ir(III) with the VQPy units. The first methodology led to copolymer P1 having fully complexed VQPy units, whereas the latter methodology allowed the preparation of terpolymers containing free and Ir(III)-complexed VQPy units (copolymer P2). The optical properties of the copolymers were studied in detail through UV-Vis and photoluminescence spectroscopy in aqueous solution. It is shown that the metal-to-ligand charge transfer (ΜLCT) emission is prevailing in the case of P1, regardless of pH. In contrast, in the case of terpolymer P2 the MLCT emission of the Ir(III) complex is combined with the pH-responsive emission of free VQPy units, leading to characteristic pH-responsive color changes under UV illumination in the acidic pH region.

A route toward processable n-type terpolymers is presented herein based on the random donor-acceptor-donor-acceptor (D-A1)-(D-A2) molecular configuration. Carbazole is utilized as the electron donating unit (D) combined with perylene diimide (PDI) as the first electron acceptor (A1) and either one of two different benzothiadiazole (BTZ) derivatives ( di-thienyl substituted-BTZ and di-3,4-ethylenedioxythienyl substituted-BTZ) as the second electron accepting unit (A2). Increasing the content of the PDI co-monomer resulted in terpolymers of higher molecular weights, enhanced solubility, and stronger n-type character. The physicochemical properties of the random PDICz-BTZ derivatives are fine-tuned based on the feed ratio of the co-monomers. Photodiode devices were demonstrated, having photoactive layers composed of the rich in PDI terpolymer, namely, P4 having a 75% PDI content, and the PCE10 electron donor, under various ratios. For a range of P4 blend compositions, UV-Vis, is spectroscopy confirmed the strong absorption of the blend films across the 350-800 nm spectral region, and AFM imaging verified their low surface roughness. The study of the electro-optical device properties identified the 1:2 blending ratio as the optimum PCE10:P4 combination for maximum charge photogeneration efficiency. Despite the relatively deep LUMO energy of the n-type P4 terpolymer (E-LUMO = -4.04 eV), trap-induced charge recombination losses were found to limit the PCE10:P4 photodiode performance. Unipolar devices of the P4-alone exhibited hole and electron mobility values of 2.2 x 10(-4) and 6.3 x 10(-5) cm(2) V-1 s(-1), respectively.

We have investigated semiconducting aromatic aliphatic polyethers based on either distyrylanthracene (Polymer A) or distyrylanthracene, distyrylbenzothiadiazole and distyrylcarbazole (Terpolymer B) chromophores separated by aliphatic undecane spacers that were deposited as thin films onto PEDOT:PSS by X-ray Photoelectron spectroscopy (XPS), depth-profiling XPS, and Reflection Electron Energy Loss Spectroscopy (REELS) techniques. XPS measurements demonstrated the quality of the prepared films. They also showed that for the Terpolymer B sample there is an excess of PSS dopant in the film surface, which was further corroborated through argon ion sputtering process coupled to the XPS acquisition. N1s XPS results suggest that sulphonic groups present in the PSS molecule might interfere in the Terpolymer B backbone by protonating their nitrogen atoms. From REELS data, pi - plasmon peaks were derived for Polymer A and Terpolymer B thin films. In addition, Spectroscopic Ellipsometry and Photoluminescence Spectroscopy were applied for the evaluation and the determination of the optical properties as well as the thickness of the photoactive polymeric films and the emission characteristics, respectively.

In the present investigation, a binary strategy for the development of wavelength-selective semi-transparent dye-sensitized solar cells (DSSCs), with a proper transmittance in the region of photosynthetic active radiation, for greenhouses-oriented applications is examined. Two new low-cost triphenylamine-based dyes and a highly transparent iodine-free electrolyte are proposed as alternatives to the conventional expensive ruthenium-based dyes and yellowship iodine-based electrolytes for attaining more suitable optical characteristics to DSSCs that are intended to be used as cladding materials in greenhouses. The spectral engineered DSSCs demonstrated a quite high external quantum efficiency (almost 85%) in the whole blue and green part of the visible spectrum, while providing high transparency (up to 55%) in the red part, which is of the most important ones for the process of photosynthesis. The present work demonstrates that the development of solar cells with an energy conversion efficiency on the order of 6% combined with a crop growth factor of almost 35% is feasible. To the best of the authors’ knowledge, these combined performance parameters are of the best-reported ones for “agrivoltaics”, giving new insights for developing energy-autonomous greenhouses, further suggesting that spectral engineering is an effective strategy to improve the performance of DSSCs for niche applications.

For the first time in dye-sensitized solar cell (DSSC) technology, a di-carbazole-based dye was synthesized and evaluated for its usage as a potential sensitizer for the development of wavelength selective semi-transparent DSSCs for greenhouses-oriented applications. The dye was designed to demonstrate a blue light absorption, allowing a high transmittance in the red region of the visible light, even after its adsorption on the anode semiconductor, which is the most important one for the photosynthetic action of the plants. The application of the new dye to DSSCs was examined using either a high-performance iodide-based electrolyte or a highly transparent iodine-free electrolyte to determine a good balance between electric power generation and device transparency. The spectral engineered DSSCs demonstrated quite promising characteristics, providing a high external quantum efficiency (higher than 70%) in the whole blue–green region of the visible light, while allowing high transparency (up to 55%) in the red region, where the second peak in the absorbance spectrum of chlorophyll is located. Finally, the derived results were discussed under the consideration of important metrics for this niche application, including the transparency of the solar cells in the region of photosynthetic active radiation and the attained crop growth factor. The present work constitutes one of the few comprehensive studies carried out up to now in the direction of the development of 3rd generation “agrivoltaics” for their possible integration as cladding materials in energy-autonomous greenhouses.

In this study, novel copolymers consisting of blue and red chromophores are presented to induce emission tuning, enabling the definition of white light emission in a single polymeric layer. These aromatic polyether sulfones exhibit high molecular weights, excellent solubility and processability via solution deposition techniques. In addition, by carefully controlling the molar ratios of chromophores composition, the energy transfer mechanism, from blue to red chromophores, takes place enabling us to define properly the emission covering the entire range of the visible spectrum. The optical and photophysical properties of the monomers and copolymers were thoroughly investigated via NIR-Vis-far UV Spectroscopic Ellipsometry (SE), Absorbance and Photoluminescence (PL). These copolymers are used as an emissive layer and applied in solution-processed WOLED devices. The fabricated WOLED devices have been subsequently studied and characterized in terms of their electroluminescence properties. Finally, the WOLED devices possess high color stability and demonstrate CIE Coordinates (0.33, 0.38), which approach closely the pure white light CIE coordinates.

White Organic Light-Emitting Diodes (WOLEDs) have attracted an enormous interest because they can be implemented in numerous lighting applications as next-generation light sources. In this work, terpolymers bearing blue, yellow and red chromophores are used for the fabrication of WOLED devices. These systems provide easy tuning of white color by changing weight ratios between the chromophores. The optical and opto-electronic characterization is carried out by near infrared–visible-far ultraviolet (NIR–Vis–FUV) Spectroscopic Ellipsometry (SE), Photoluminescence (PL), and Electroluminescence (EL), whereas the structural characterization is achieved by Atomic Force Microscopy (AFM), to provide valuable information toward the optimization and functionalization of these WOLED devices.

In this work, the optical properties of red-light emitting materials used for active layers in functional red OLED devices were researched. The investigated materials are: a synthesized lab scale complex vinyl-quinoline pyridine homopolymer with Ir P[QPy-Ir-(PPy)2], as well as two commercially supplied materials, Poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). The samples were spin-coated on ITO/glass substrates. The characterization of the materials was carried out via Spectroscopic Ellipsometry (SE), Photoluminescence Spectroscopy (PL) and Electroluminescence Spectroscopy (EL). Through SE analysis the film thickness, the optical properties and the dielectric function were obtained. PL and EL spectra were derived and evaluated in terms of the emission profile and characteristics of the different photoactive materials. Finally, the colour stability and selectivity of each material were determined, and a comparative study of the red-light emitting materials was conducted.

A face-to-face porphyrin dimer, (H2P)2 "porphyrin tweezer", was explored as a photo- and redox-responsive host for the molecular recognition of an azafullerene (C59N) derivative bearing an amphoteric pentafluoroquinoline (FQ) domain. The intramolecular electronic coupling between the FQ substituent and the C59N cage, within the newly synthesized C59N-FQ dyad was evaluated, while the neutral and protonated form of the covalently attached FQ moiety were utilized as recognition motifs for the (H2P)2 tweezer. Complementary photophysical and electrochemical techniques were applied to investigate the electronic communication between the porphyrin-dimer (H2P)2 tweezer and the azafullerene cage as mediated by the FQ unit.

Acid-doped reinforced polymer electrolyte membranes for high-temperature polymer electrolyte membrane fuel cell applications (HT PEMFCs) are presented and spectroscopically studied. Fully aromatic polyethers are employed bearing main chain pyridine units as the proton accepting sites, which have two different substitution patterns of the pyridine units, namely, 2,5- or 2,6-pyridine. This fact enables control of the solubility and of the acid doping ability of the polymeric membranes. Reinforcement is accomplished via incorporation of a PTFE woven fabric during the casting procedure for fabrication of the membranes. High acid uptake of the reinforced membranes was maintained for the 2,6-pyridine-based copolymers with high pyridine unit content. Studies of the swelling behavior of these reinforced membranes revealed that they expand mainly along the z-axis, which helps to avoid extensive damage in case of humidity or temperature changes during the fuel cell operation. Additionally, spectroscopic techniques are employed, namely, X-ray photoelectron spectroscopy, X-ray photoelectron spectroscopy with depth profile, near-edge X-ray absorption fine structure, and reflection electron energy loss spectroscopy, for the in-depth study of the two copolymer membranes doped with phosphoric acid. Through these spectroscopic evaluations, modifications in the membranes’ chemical structure, orientation, composition, and electronic structure after the reinforcement and doping processes were elaborated and unveiled.