# Luminescence Materials for Dye-Sensitized Solar Cells: Advances and Directions
## 4 Luminescent Materials in DSSCs
### Advances and Research
When applied as down-converting photoactive electrodes in DSSCs, the overlaid PBWO/TiO\({}_{2}\) photoactive anodes demonstrated a notable improvement in the total power conversion efficiency of the developed solar cell to 8.08% for a doping concentration of y = 5 mol % of the Pr\({}^{3+}\), as shown in Figure 5. It was shown that the Pr\({}^{3+}\) significantly boosted the efficiency of DSSCs. The general photovoltaic performance with and without the down-converting material is presented in Table 1. An asterisk (*) is used to denote the device with the highest efficiency. Research by [PERSON] et al. [57] proposed a promising new type of up-conversion phosphors (UCPs)-TiO\({}_{2}\) composite photo-anode for increased light harvesting in DSSCs. The significantly increased light harvesting was attributed to the outstanding light scattering and the added NIR light effect of the up-conversion of \(\beta\)-NaYF\({}_{4}\):Yb\({}^{3+}\), Er\({}^{3+}\) nanoparticles. However, adding such UCPs to photo-anodes caused the charge recombination at the photo-anode-electrolyte interface to aggravate. The undesirable effect was reduced by coating UCPs with a thin layer of TiO\({}_{2}\). The weight ratio of 15% was the optimum concentration for UCPs/TiO\({}_{2}\) to produce high performance in the DSSC. The associated DSSC produced a power conversion efficiency of up to 7.17%, which is much better than 5.45% for the bare TiO\({}_{2}\) nanoparticle-based device. [PERSON] and [PERSON] [58] demonstrated the impact of the BiYO\({}_{3}\):Er\({}^{3+}\)/Yb\({}^{3+}\) up-converting (UC) nanoparticles in enhancing the performance of DSSCs. The power conversion efficiency of the DSSCs with the incorporation of the UC was raised from 5.73% to 6.20%. The primary cause of the improvement was the ability of the UC to convert NIR light to visible light. According to the findings of the study, it is feasible to add UC nanophosphors to DSSC in order to enhance their photovoltaic capabilities and the dye capability for light harvesting. [PERSON] et al. [59] incorporated Y\({}_{2}\)O\({}_{3}\):Ho\({}^{3+}\)/Yb\({}^{3+}\) into TiO\({}_{2}\) to build DSSCs and a comparison of their photovoltaic performance was performed. The ability of the UC phosphor to harness NIR-visible light has been observed to increase the power conversion efficiency of the DSSC by 10.33% when compared to the bare TiO\({}_{2}\) DSSC. The efficiency was raised from 8.9% to 9.82% by the integration of the UC phosphors, as shown in Figure 6a. This means that the efficiency of the bare DSSC was 8.9% and the integration of the UC phosphor enhanced the efficiency to 9.82%. The efficiency was enhanced as a result of the rise in the N719 spectral sensitivity. Compared to the bare TiO\({}_{2}\)-based cell, the DSSC integrated with the UC showed better durability, as presented in Figure 6b. The higher durability was perceived due to the effect generated by the incorporation of UC phosphors into the TiO\({}_{2}\), leading to a higher infiltration of electrolytes and prevented the evaporation of electrolytes \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**y mol PBWO Electrodes** & \(\mathbf{V_{ex}}\) & \(\mathbf{J_{ex}}\) & \(\mathbf{V_{max}}\) & \(\mathbf{J_{max}}\) & \(\mathbf{FF}\) & **Dye Absorbed [M] \(\times\) 10\({}^{-5}\)** & **Eff (y) \%** \\ \hline
0.00 & 0.572 & 14.40 & 0.343 & 12.15 & 0.51 & 2.35 & 4.17 \\
0.01 & 0.504 & 18.57 & 0.350 & 16.78 & 0.62 & 3.47 & 5.87 \\
0.03 & 0.514 & 20.22 & 0.364 & 18.16 & 0.63 & 5.06 & 6.51 \\
0.05 \({}^{*}\) & 0.522 & 23.94 & 0.380 & 21.25 & 0.65 & 8.72 & 8.08 \\
0.07 & 0.513 & 22.56 & 0.385 & 18.71 & 0.62 & 6.74 & 7.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Photovoltaic characteristics of DSSCs based on the different PBWO/TiO\({}_{2}\) down-converting photoactive electrodes [56]. Figure 5: Photocurrent–voltage (J–V) curves of the DSSC based PBWO/TiO2 down-converting photoactive electrodes [56]. [PERSON] et al.