# Sustainable Organic Dyes from Winemaking Lees for Photoelectrochemical Dye-Sensitized Solar Cells
## 4 Conclusions  
The present work aimed to exploit and valorise the main waste product of a winery, recovering the lees of red and white wines to realize DSSC solar cells and generate a renewable and sustainable  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample Name** & **Jsc (mA/cm2)** & **Voc (V)** & **Efficiency (\%)** \\ \hline Grape [37] & 1.81 & 0.427 & 0.33 \\ Giacche grapes [9] & 3.06 & 0.333 & 0.57 \\ Port wine [38] & 0.15 & 0.385 & 0.025 \\ R-S & 1.47 & 0.492 & 0.45 \\ R-RT2 & 1.12 & 0.419 & 0.35 \\ \hline \hline \end{tabular}
\end{table}
Table 4: DSSCs parameters using wine and grapes as dye. Relative uncertainties of our DSSC are less than 10%.  
Figure 11: J-V and P-V curves of the DSSC prototypes realized with red winemaking lees extract. R-RT and R-RT2 are extracts of two different types of red wine lees, both at RT.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample Name** & **Jsc (mA/cm2)** & **Voc (V)** & **FF (\%)** & **Efficiency (\%)** \\ \hline R-RT & 0.46 & 0.402 & 55 & 0.10 \\ R-S & 1.47 & 0.492 & 62 & 0.45 \\ W-RT & 0.43 & 0.357 & 38 & 0.06 \\ W-S & 0.75 & 0.477 & 64 & 0.23 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Parameters of DSSCs prototypes obtained from J-V and P-V curves. Relative uncertainties are less than 10%.  
photoelectric current. A nanostructured mesoporous titanium dioxide powder was synthetized by the sol-gel process, being thermally treated at different temperatures and characterized by several techniques. Organic dyes (tannins, anthocyanins, polyphenols, catechins), extracted from winemaking lees, were adsorbed on the TiO\({}_{2}\) nanoparticles. DSSCs prototypes were then assembled and tested under simulated solar light irradiation and the generated electric current was measured.  
The photocurrent density and photovoltage obtained are comparable with the typical values of an organic dye sensitized solar cell built with dyes that were extracted from vegetables and fruits. More interesting is that these dyes are largely available and cost effective, since being recovered from a waste otherwise to be disposed of, opening up a perspective of feasibility for inexpensive and environmentally friendly dye solar cells. A sustainable and low-cost alternative to the traditional systems could be obtained while using such a peculiar class of organic dyes that were derived from winemaking lees, transforming an agri-food waste in resource to generate green electrical energy.  
Conceptualization, M.M., E.M. and S.M.; data curation, M.M.; formal analysis, M.M. and E.B.; funding acquisition, E.M. and S.M.; investigation, M.M., E.M., T.E.C. ([PERSON]) and E.B.; methodology, M.M.; project administration, E.M.; resources, A.T., E.C. ([PERSON]), E.C. ([PERSON]), E.R.-C.; supervision, E.M.; visualization, M.M.; writing--original draft preparation, M.M. and E.M.; writing--review and editing, E.C. ([PERSON]), E.C. ([PERSON]), E.R.-C. and S.M. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The authors would like to acknowledge [PERSON], [PERSON] and [PERSON] of Serena Wines 1881 srl (Conegliano, Italy) for the valuable and constructive suggestions during the planning and development of this research work. M.M. and E.M. acknowledge the financial support of Project 2120-1-11-2018 received from European Social Fund (FSE) and Veneto Region. E.R.-C. thanks to project RTI2018-099668-BC22 of Ministerio de Ciencia, Innovacion y Universidades and FEDER funds.  
The authors declare no conflict of interest.