The Study Of Organic Ionic Plastic Crystals In Solid-state Dye-sensitized Solar Cells

Dye sensitized solar cells (DSSCs) have been considered as a new type of solar cellsthat can replace traditional silicon photovoltaic cells, because of their high energyconversion efficiency, relatively low production cost, and ease of fabrication. Theelectrolyte as a component of the DSSCs plays an important role on the performance of thedevices. The photoelectric conversion efficiency of DSSCs has achieved more than12%with the liquid electrolyte. However, the evaporation and leakage of solvent applied inliquid electrolyte-based DSSCs seriously impact the long-term stability of cells. What’smore, the traditional (I/I3) redox couple has some drawbacks, such as the corrosion of themetal electrode and the strong absorption of visible light.In order to solve these problems, ionic organic plastic crystals and organic iodine-freeredox couples were synthesized and applied for DSSCs. Main contents mainly concludethree parts as follows:(1) Organic ionic plastic crystal,1-propyl-1-meth-ylpyrrolidinium iodide (P12I), wasdoped with7nm silica nanoparticles and1-ethyl-3-methylimidazolium iodide (EMII), forthe preparation of SiO2/EMII/P13I solid-state electrolytes for dye-sensitized solar cells(DSSCs). The fabricated solid-state DSSCs yield a high power conversion efficiency (PCE)of5.25%under simulated air mass1.5solar spectrum illuminations at50mW cm2, andthe DSSCs show good stability after an accelerating aging test.(2) A new family of organic ionic plastic crystals (OIPCs) based on bis-quaternaryammonium cations was synthesized and characterized. The length of alkylene spacersbetween two ammonium units and alkyl linked ammonium units was changed to obtainmaterials with different thermal properties. The synthesized OIPCs were characterized bydifferential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-raydiffraction (XRD).(3) An iodine-free organic redox couple based on thiopropionic acid was synthesizedand applied for dye-sensitized solar cells (DSSCs). The resultant DSSCs containing this organic redox couple (0.1M/0.1M) without Li+ions exhibit a high overall powerconversion efficiency of6.70%and8.10under the simulated air mass1.5solar spectrumillumination at100mW cm-2and50mW cm-2, respectively. However, the PCE of DSSCsbased on I/I3only reach1.69%and1.93%at same condition.