| It is well-known that, liquid electrolyte exists some undesirable problems for practical applications, such as the long-term durability and operation stability of devices. To solve these problems, this paper prepared two kinds of polymer electrolytes based on4-vinylpyridine and also prepared quasi-solid state dye sensitized solar cells (DSSC) based on the home-made TiO2and Pt electrodes. The structure and performance of the electrolytes and cells were systematically investigated.In the first part, TiO2and Pt electrodes with good performance were prepared by the methods of screen printing and.drop-casting. Firstly, we optimized the formula of TiO2slurry (P25and larger diameter TiO2particles) and the method of screen printing to prepare the TiO2electrodes, and it was found that the optimal structure is two layers of light-scattering TiO2particles covering six layers of P25TiO2particles, and the total thickness of TiO2particles is13μm By comparing the corresponding photoelectric conversion efficiency (η) of solar cells, the performance of TiO2electrodes we prepared was as good as that we purchased; the performance of Pt electrodes we prepared was better than that we purchased.In the second part, the gel electrolyte P(4-VP-MMA)/P(VDF-HFP)/LiI/I2/MPN was prepared and used for assembling DSSC. The influence of4-VP:MMA and P(4-VP-MMA):P(VDF-HFP) mass ratio was investigated, and the optimum formula of gel electrolyte is that, mass ratio of monomer4-VP and MMA was3:7, and the mass ratio of P(4-VP-MMA) and P(VDF-HFP) was10:7, respectively. Over the home-made DSSC, the voltage of open circuit (Voc) was0.72V, short circuit current density (Jsc) was6.03mA.cm-2, and photoelectric conversion efficiency (η) was2.3%. TGA studies showed that the heat resistance of gel electrolyte was better than that of liquid electrolyte. In order to study the structure of the gel electrolyte, a variety of solid content of the gel electrolytes were characterized by SEM, and it was shown that the properties of solar cells were largely affected by the morphology of polymer backbone. Additionally, the IPCE results showed that the light absorption, charge collection and capture efficiency of the DSSC was attracted by the structure of dye molecules and electrodes.In the third of part, gel electrolyte based on P(4-VP-HEMA)/LiI/I2/GBL was prepared and used for assembling DSSC, in order to study the relationship between polymers with hydrogen bonds and gel electrolyte. The morphology of polymer was observed by SEM, and the SEM images showed that of the "backbone" polymer was similar to that in the second part, and lower solid content caused higher performance of DSSC. At the same time, we have explored the optical properties of solar cells with different4-VP and HEMA mass ratio, and the optical mass ratio is4-VP:HEMA=1:3.Meanwhile, in order to characterize the influence of additives on the properties of the polymer gel electrolyte clearly, TBP,4-VP and PY have been studied in this paper. The results showed that additives have similar effect both in gel electrolyte and liquid electrolyte. TBP and PY could improve Voc, Jsc and η, however,4-VP had the opposite effect. On this basis, this paper inferred the reaction mechanism of4-VP and redox couple (I-F/I3-).In addition, the P(4-VP-MMA) and P(4-VP-MMA)/P(VDF-HFP) were characterized by1HNMR, IR, TGA and IPCE. The structure-performance relationship of electrolyte was investigated, as well as the relationship between the temperature and conductivity/photosensitivity of dyes. |
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