Daniele Franchi

This study integrates life cycle assessment and life cycle costing to evaluate the environmental and economic performance of three emerging photovoltaic technologies: dye‐sensitized solar semifabricates (DSSMs), perovskite solar semifabricates (PSMs), and four‐terminal DSSM/PSM tandem semifabricates. The cradle‐to‐gate analysis combines life cycle inventories based on primary laboratory and pilot‐scale data with a scaling‐up model linking experimental results to preindustrial and prospective industrial scenarios. Laboratory energy consumption is quantified using equipment operating times, nominal power ratings, and correction factors reflecting operating conditions. Normalization to the effective processed area enables direct comparison and scalability assessment. Results show that PSMs have the lowest environmental impacts and cost (2.66 × 10 ¹ kg CO ₂ eq, 2.01 × 10 ² CTUe, 8.69 × 10 ⁻⁴ kg Sb eq, 5.90 × 10 ² Eur/kWp), mainly due to the absence of noble metals. DSSMs are penalized by Ag, Pt, and double fluorine‐doped tin oxide glass, reaching 2.88 × 10 ¹ kg CO ₂ eq, 5.27 × 10 ² CTUe, 5.44 × 10 ⁻³ kg Sb eq, and 3.61 × 10 ³ Eur/kWp. Tandem semifabricates inherit hotspots from both subsystems but benefit from higher efficiency. At 1 kWp normalization, efficiency becomes the main differentiating factor: PSMs perform best, DSSMs worst, and tandems intermediately. The framework supports sustainable development of building‐integrated photovoltaics.

In this work, the highly conjugated pentacyclic [1]benzothieno[3,2‐ b ]thieno[2,3‐ f ][1]benzothiophene ( TBTBT ) moiety has been introduced, for the first time, as a mild donor group in the structure of three donor‐acceptor organic dyes, named PCD1‐3 . After dye design assisted by DFT and TD‐DFT computational studies, the fused TBTBT system with the appropriate substitution pattern was synthesized by means of a three‐step sequence, featuring a Pd‐catalyzed direct arylation of 1‐bromo‐2‐(methylsulfinyl)benzene and a subsequent interrupted Pummerer reaction as the key steps. Further elaboration of the dyes’ structures was then achieved by application of additional C(sp ² )‐C(sp ² ) direct arylation protocols, thereby making the overall pathway particularly concise. Spectroscopic and electrochemical characterization revealed that dyes PCD1‐3 presented the appropriate properties for employment as photosensitizers in dye‐sensitized photovoltaic cells (DSSCs) for indoor applications. Preliminary tests conducted on DSSCs fabricated with the new dyes highlighted differences in their compatibility with electrolyte solutions of different compositions, as well as in their response to different indoor and outdoor (simulated) light sources, with the best results obtained under illumination with a cold white LED (900 lux).

We introduce a time-resolved Monte Carlo simulation framework for designing fluorescent concentrators (FCs) as optical antennas (OAs) in optical wireless communication (OWC). Unlike traditional analytical models, it captures both collection efficiency and temporal response, enabling optimization of dye concentration and geometry. The model is validated against experimental data obtained for two sets of OAs based on Lumogen Red 305 (LR305) and DQ1 dyes over a wide range of fluorophore concentrations, and it consistently reproduces the measured behavior by explicitly accounting for the interplay between key FC parameters, including fluorescence lifetime, quantum yield, absorption and emission spectra, and reabsorption dynamics. This approach not only provides an accurate characterization of FC performance for OWC but also represents a powerful tool for tailoring FCs to specific OWC applications.

A covalent organic dyad was designed, synthesized, and characterized. When used as a sensitizer in DSSCs, efficient energy transfer from the antenna to the dye results in higher light-harvesting efficiency and photocurrent compared to the dye alone.

Optical Antennas (OAs) based on Fluorescent Concentrators (FCs) promise a revolution in the deployment of Visible Light Communication (VLC) and Optical Wireless Communication (OWC), due to their inherent advantages over conventional receivers in terms of exceedingly larger field of view (FoV) and optical gain (OG). Whilst FC-based OAs have been demonstrated in VLC applications in a wealth of works embedding monochromatic UV and Blue LED sources, a detailed study demonstrating the performances of OA in white-light VLC (WLC) applications, which is at the basis of the deployment of VLC for Internet of Things (IoT), 6G and pervasive networks, is still lacking. In our work we present and test two 50 mm x 50 mm OAs for WLC, based on two of the most effective fluorophores (Lumogen Red 305 F and DQ1, respectively) used in Luminescent Solar Concentrator (LSC) applications. We perform a detailed characterization of intrinsic and VLC performances, comparing the results with a novel Monte Carlo model accurately describing the photon conversion and propagation processes. Whilst DQ1 represents the most suited solution for high-speed VLC with UV/blue LEDs, our results highlight excellent performances of Lumogen-based OA in white-light settings, outpacing the performances of ordinary photodiode-based receivers. Our results pave the way towards the full-fledged deployment of VLC in IoT applications, where the availability of detectors with large-area, wide FoV and enhanced OG covering the white LEDs emission is a central element.

Among the emerging photovoltaic (PV) technologies, Dye-Sensitized Solar Cells (DSSCs) appear especially interesting in view of their potential for unconventional PV applications. In particular, DSSCs have been proven to provide excellent performances under indoor illumination, opening the way to their use in the field of low-power devices, such as wearable electronics and wireless sensor networks, including those relevant for application to the rapidly growing Internet of Things technology. Considering the low intensity of indoor light sources, efficient light capture constitutes a pivotal factor in optimizing cell efficiency. Consequently, the development of novel dyes exhibiting intense absorption within the visible range and light-harvesting properties well-matched with the emission spectra of the various light sources becomes indispensable. In this review, we will discuss the current state-of-the-art in the design, synthesis, and application of organic dyes as sensitizers for indoor DSSCs, focusing on the most recent results. We will start by examining the various classes of individual dyes reported to date for this application, organized by their structural features, highlighting their strengths and weaknesses. On the basis of this discussion, we will then draft some potential guidelines in an effort to help the design of this kind of sensitizer. Subsequently, we will describe some alternative approaches investigated to improve the light-harvesting properties of the cells, such as the co-sensitization strategy and the use of concerted companion dyes. Finally, the issue of measurement standardization will be introduced, and some considerations regarding the proper characterization methods of indoor PV systems and their differences compared to (simulated) outdoor conditions will be provided.

Climate change mitigation on a global scale will only be possible through the achievement of ambitious decarbonisation goals, requiring an energy transition that involves switching from fossil fuels to clean fuels such as hydrogen. The photocatalytic approach is one of the most studied methods for directly converting sunlight into hydrogen. In this work, we present the synthesis, characterization, and application of the PTZ1‐HA dye, which was obtained by replacing the terminal conventional carboxylic anchoring moieties of a previously studied phenothiazine‐based dye (PTZ1) with hydroxamic acid functionalities. The photoinduced performance of the two dyes as photosensitizers was compared in both dye‐sensitized solar cells and dye‐sensitized photocatalytic systems. PTZ1‐HA‐sensitized photocatalysts showed improved stability in hydrogen generation due to the introduction of the hydroxamic acid as an alternative anchor group, which was shown to slow down hydrolysis in aqueous media. Even though the light harvesting ability of PTZ1‐HA was lower than that of PTZ1, the higher stability of PTZ1‐HA‐sensitized devices allowed for improved photocatalytic generation of H₂ over prolonged periods. The superior long‐term efficiency of the hydroxamic acid based dye is important in view of potential practical applications.

Two novel organic sensitizers for Dye-Sensitized Solar Cells (DSSC), called TP1 and TP2, based on the electron-poor thieno[3,4-b]pyrazine (TPz) π-bridge and the electron-rich N,N-bis(4-(hexylthio)phenyl)aniline (TPA) were designed following two different approaches: the classical D-A-π-A design and a symmetric structure with double anchoring functions. Both compounds were prepared exploiting short synthetic pathways based on direct arylation strategies and possibly one-pot desymmetrization. The two novel dyes displayed opposite optical properties: a broad and intense light absorption over the entire visible spectrum for TP1, and a localized absorption that peaked in the center of the visible region for TP2, resulting in a pitch-dark coloration and a green tone, respectively. When assembling the photovoltaic devices, different electrolyte compositions were explored to enhance the optical properties of the dyes. Power conversion efficiencies as high as 5.2% under full sun intensity were recorded for small test devices. The composition of the light transmitted through the TP2-containing transparent DSSC fits well with the human eye sensitivity spectrum, thus fulfilling the transparency requirements for building-integrated photovoltaics (BIPV).