Modification Of Polymer Electrolyte And Perovskite For Mesoscopic Solar Cell

Mesoscopic solar cell is a new kind of solar cell based on mesoscopic inorganic or organic semiconductors with three-dimentional interpenetrating network structure. Due to its nanoporous structure, this solar cell has very large specific surface area, which makes it more beneficial for optical absorption and charge seperation.Dye-sensitized solar cell (DSSC) is a typical kind of mesoscopic solar cell. DSSC has been considered as one of the most promising new-generation solar cell technologies due to its simple fabrication process, low-cost raw materials, and colorful transparency. Over two decades of research, the highest certified efficiency of DSSC based on liquid-state electrolyte reached to11.9%. However, the liquid-state electrolyte suffers from problems such as solvent evaporation, long-term stability of the devices, expensive plantinized electrode and so on, thus limits the commercial development of DSSC.Compared with traditional DSSC, all-solid-state DSSC with, monobasal structure based on carbon counter electrode is a kind of mesoscopic solar cell with more market potential, which characterizes in that, photoanode, spacer layer and counter electrode are prepared by screen-printing technology on a single conductive substrate, and then dye is sensitized and electrolyte is filled in. The manufacture technology of monobasal DSSC is simpler, the carbon electrode is cheaper, and the quasi-solid-state or solid-state electrolyte filled in avoids issues such as the leakage of electrolyte.In this thesis, we developed a series of composited and modified electrolyte for monobasal DSSC, so that the ionic conductivity of composite electrolyte was increased, but also the interfacial contact between the electrolyte and electrodes was improved, leading to the enhancement of power conversion efficiency of solar cells. Besides, we successfully introduced novel perovskite materials as light harvester and charge tranporter into monabasal solid-state mesoscopic perovskite solar cells, power conversion efficiency of12.9%was achieved by modification of perovskite.The main contents of this thesis are listed as following:The thickness of work electrode TiO2layer, the reflectance of ZrO2layer and catalytic activity of carbon electrode were investigated for monobasal solid-state DSSC based on PEO/PVDF polymer electrolyte. By optimizing the molecular weight of PEO, the properties of polymer electrolyte were improved and the efficiency of the device was enhanced to2.82%. Reproducibility research of device fabrication indicated that the deviation of ten devices’efficiencies prepared by screen-printing technology was below6%.A noval nanomaterial of alkyl imidazolium iodide-functionalized silica (SiO2-Iml) was synthesized and incorporated in PEO/PVDF polymer electrolyte. FT-IR spectra, scanning electron microscope, differential scanning calorimetry and ionic conductivity characterizations indicated that the surface morphology SiO2-ImI composite polymer electrolyte (CPE) was more uniform, and the conductivity of SiO2-ImI CPE is greatly increased compared with unmodified polymer electrolyte. As a result, a power conversion efficiency of3.83%was obtained with SiO2-ImI CPE based monobasal solid-state DSSC.The graphene nanosheet was synthesized by chemical redox methods and incorporated in PEO/PVDF polymer electrolyte. By assembling monobasal DSSC with grahene composite polymer electrolyte, the open-circuit photovoltage of the device was greatly improved. Replacing the normal carbon electrode by graphene modified carbon electrode, the fill factor of the device was enhanced and the higher efficiency of3.98%was achieved.Two organic sulfide redox couples were introduced and characterized by UV-Visable spectra and electrochemical method. Transparent quasi-solid-state devices were assembled with polymer gel electrolyte based on organic sulfide redox couples and PEDOT counter electrode prepared by electropolymerization. The properties of the polymer gel electrolyte were optimized and the efficiency of4.26%was obtained. This is the first report about quasi-solid-state DSSC based on sulfide redox couples so far.A hole-conductor-free fully printable mesoscopic perovskite solar cell based on carbon counter electrode was constructed and formamidinium lead trihalide perovskite (FAPbI3) with lower bandgap was firstly introduced as the light harvester, yielding an efficiency of11.9%. By optimizing mixing ratio of the FAbI3and methylammonium lead trihalide (MAPbI3), power conversion efficiency of12.9%was achieved with this low-cost fully printable mesoscopic solar cell.