## 3 Results  
Table 2 shows the results of the ionic conductivity measurements for the different GPEs used to build the DSSCs. The value of the reference electrolyte was taken from Reference [27], where it was measured under identical conditions. For each sample, the three assembled DSSCs were studied for 21 days to examine the most efficient DSSC per sample and their reproducibilities. Therefore, the temporal efficiency progressions over the first 21 days of all investigated DSSCs of this paper are depicted in Figure 1. The denomination of GPEs corresponds to Table 1. Regarding samples 1 and 5 (Figure 1a,c) the differences in the efficiencies were relatively minor compared to the deviations in the other samples. Especially large deviations occurred with respect to sample 3 (Figure 1b), sample 4 (Figure 1c), and sample 8 (Figure 1d). The differences in the efficiency curves of identical DSSCs are shown in Figure 1 and indicate the low reproducibility of the DSSCs built here. Nevertheless, in order to investigate the long-term stability of the DSSCs depending on the appropriate electrolyte system, the most efficient DSSC per sample, indicated with \"a\", was selected for closer examination. From the I-U curves, short-circuit current (ISC), open-circuit voltage (UOC) and the maximum power point (PMP) can be estimated. The central point of discussion is the long-term stability of the individual non-toxic GPEs while the DSSC maintains a high level of efficiency in comparison to the other DSSCs tested. Figure 2 shows the efficiency progression of pure PAN as a gelling agent in the electrolyte, labeled sample 3, in comparison with two blends of PAN/PEO (samples 1 and 2). In this regard, sample 1 contains more PAN, PEO and KII:2 overall than sample 2, while having a similar ratio. Having the highest DMSO concentration, sample 2 had the highest efficiency during the first few days but decreased rapidly during the first two weeks, with an unsuspected increase after these two weeks and dropping again to values before after three weeks. In contrast, the efficiency of sample 1 increased significantly during this time, peaking highest at around the third week, while sample 3 shows little variation during this period. Noticeable is the efficiency curve of samples 2 and 3 in approximately the second month of measurement, because after a decrease for about two weeks, the efficiency increased again to a similar value as before. Since the efficiency of a DSSC cannot increase apart from the pore filling process [10, 26, 28, 29], in which the efficiency does not decrease before it increases, measurement deviations can be assumed as a possible explanation. In the long run, sample 1 showed the best results in efficiency and long-term stability compared to all other DSSCs containing PAN. Figure 1: Efficiency progressions over the first 21 days of the three assembled DSSCs per sample: (**a**) sample 1 (PAN/PEO GPE) and the reference (commercial liquid electrolyte); (**b**) sample 2 (PAN/PEO GPE with different ratio) and sample 3 (PAN GPE); (**c**) sample 4 (ABS/PEO GPE) and sample 5 (ABS GPE); (**d**) sample 6 (PVA/PEO GPE) and sample 7 (PVA GPE); (**e**) sample 8 (PVDF/PEO GPE) and sample 9 (PVDF GPE). The letters “a” to “c” indicate the different DSSCs per sample, where “a” denotes the best DSSC studied over 120, respectively. As an additional opportunity for comparison concerning the efficiency graphs, typical I-U curves are depicted for samples 1 to 3 in Figure 3. The I\({}_{\text{SC}}\) values of samples 1 and 3 increased until day 28 and decreased thereafter, while the I\({}_{\text{SC}}\) of sample 2 decreased until day 28 and then fluctuated slightly. This decreasing trend of sample 2 is also apparent regarding its U\({}_{\text{OC}}\), which corresponds to the efficiency progression in Figure 2. Regarding the U\({}_{\text{OC}}\) of sample 1 an increase until day 28 is again visible with slight fluctuations afterwards and the U\({}_{\text{OC}}\) of sample 3 seems to decrease slightly but constantly.