Dye-sensitized solar cells (DSSCs), as emerging photovoltaic technology, have been thoroughly and extensively investigated in the last three decades. Since their first appearance in 1991, DSSCs have gained increasing attention and have been classified as feasible alternatives to conventional photovoltaic devices due to their numerous advantages, such as cheap and simple preparation methods, the possibility of being integrated in buildings and astonishing performances under indoor and diffuse illumination conditions. Photoconversion efficiencies of up to 14% and 8% have been obtained for lab-scale devices and modules, respectively. Albeit the efforts made, these values seem arduous to be outdone, at least under simulated solar radiation. Nevertheless, recent lab-scale systems have demonstrated photoconversion efficiencies of up to 33% under indoor illumination (i.e. 1000 lux) leading to an actual Renaissance (or Revival) of these devices. It is worth mentioning that scientists in this field are developing innovative materials aiming at long-term and efficient devices, being the concept of sustainability often set apart. However, in light of effective commercialization of this technology, stability, efficiency and sustainability should be considered as the essential keywords. Nowadays, DSSCs are finding a “new way back” towards sustainability and rather a huge number of reports have focused on the preparation of green and cost-effective materials to replace the standard ones. In this scenario, the present review aims to give an overview of the most adopted strategies to enhance the sustainability of materials in classical DSSC components (e.g. sensitizer, redox couple, electrolyte and counter-electrode), including smart synthesis and deposition procedures, which currently represent utmost important topics in the scientific community.

Dye‐sensitized solar cell (DSSC) is one of the promising photovoltaic (PV) technologies for applications requiring high aesthetic features combined with energy production such as building integration PV (BIPV). In this context, DSSCs have the ability to be wavelength selective, thanks to the development of new sensitizers by molecular engineering. The long history of dye research has afforded is technology different colorations for reaching panchromatic light absorption. However, nearly 45% of radiation from sunlight lies in the near‐infrared (NIR) region, where human cones are not sensitive. This review provides the reader with key information on how to selectively exploit this region to develop colorless and transparent PV based on DSSC technology. Besides selective NIR absorbers, the triptych photoanode, counter‐electrode, and redox mediator are together contributing to reach high aesthetic features. Details of all the components, interplay, and an opinion on the technological limitations to reach colorless and transparent NIR‐DSSC are herein discussed in relationship with BIPV applications.

Most photovoltaic (PV) technologies are opaque to maximize visible light absorption. However, see-through solar cells open additional perspectives for PV integration. Looking beyond maximizing visible light harvesting, this work considers the human eye photopic response to optimize a selective near-infrared sensitizer based on a polymethine cyanine structure (VG20-C_x) to render dye-sensitized solar cells (DSSCs) fully transparent and colorless. This peculiarity was achieved by conferring to the dye the ability to strongly and sharply absorb beyond 800 nm (S₀–S₁ transition) while rejecting the upper S₀–S_n contributions far in the blue where the human retina is poorly sensitive. When associated with an aggregation-free anatase TiO₂ photoanode, the selective NIR-DSSC can display 3.1% power conversion efficiency, up to 76% average visible transmittance (AVT), a value approaching the 78% AVT value of a standard double glazing window while reaching a color rendering index (CRI) of 92.1%. The ultrafast and fast charge transfer processes are herein discussed, clarifying the different relaxation channels from the dye monomer excited states and highlighting the limiting steps to provide future directions to enhance the performances of this nonintrusive NIR-DSSC technology.