| Mesoscopic solar cells, such as dye-sensitized solar cells (DSSCs) and the later developed perovskite solar cells (PSCs) have gained much attention since they are simple and low-cost processed photovoltaic devices. Typically, a DSC consists of working electrode, electrolyte, and the counter electrode. Working electrode includes conductive substrate, mesoporous semiconductor films, and dyes. Under illumilation, electrons in the ground state of dye molecules will be excited to the excited state, and then the electrons are injected into the conduction band of semiconductor. Thus, the properties of dyes and mesoporous semiconductor films will determine the light-harvesting and power convertion efficiency (PCE) of the cell. For mesoscopic PSCs based on organometallic halide perovskites as light absorbers possess several advantages, including a direct band gap, a large absorption coefficient over a wide range of the visible spectrum, a high carrier mobility as well as ambipolar charge transport. These properties have triggered the development of PSC for efficient photon-to-electricity energy conversion. A certified PCE record over 20% was attained. The configuration and the composition of the perovskite infiltrated in the mesoporous structure both are important, which will extremely affect the PCE as well as other intrinsic charge response of the device. Thus, this work focuses on the light absorber and mosoporous framework of mesoscopic solar cells. The main contents of this thesis are listed as following:Two new ruthenium sensitizers KW1 and KW2 with triphenylamine (TPA) donor antennas into the ancillary ligands were designed and synthesized. These new dyes exhibit remarkable light harvesting capacities. The different spacer between bipyridyl and TPA-donor clearly showed an influence on the photo-physical and electrochemical properties of this class of ruthenium complexes as well as their interface behaviors on the TiO2, which were scrutinized by impedance and transientphotovoltage decay measurements.Mesoporous TiO2 beads possessing dual functions of high dye loading and scattering effect have been prepared and employed as electrode for sensitized solar cells. Due to the unique characteristics of the mesoporous TiO2 beads, enhanced the light harvesting within the electrodes and improved charge collection can be achived, thereby increasing the photon-to-current conversion efficiency compared to DSSCs with photoanode prepared with nanoparticle single layer.Printable mesoscopic perovskite device using MAPbI2Br (MA=CH3NH3) as light absorber and hole conductor was demonstrated. Compared to MAPbI3, the incorporation of bromine in mixed halide perovskites led to a phase transition with a larger bandgap and longer charge carrier lifetime, which is beneficial to the enhancement of Voc and the stability against humidity in air.Printable mesoscopic perovskite devices based on MAPbI3-xBrx perovskites through a simple and facile post-synthetic halide exchange process to modify the compositional elements of the perovskite material. By incorporating Br into perovskites infiltrated in mesoporous TiO2/Al2O3/Carbon architecture, a prolonged charge carrier lifetime and improved charge collection resulted in an improved PCEs. A reduced anomalous hysteresis in the J-V curve measurement has been demonstrated in the PSCs based on MAPbI3-xBrx perovskites. Electronic impedance spectroscopy was applied to understand the internal electrical processes in such devices.Printable mesoscopic PSC device with a p-type NiO layer inserted between insulating layer and carbon electrode was demonstrated. The TiO2/Al2O3/NiO/Carbon architecture is entirely constructed with inorganic metal oxides in combination with carbon counter electrode by fully printable techniques. A reduced interfacial charge recombination was observed in quadruplelayer mesoscopic PSC devices with TiO2/Al2O3/NiO/Carbon in comparison with device structure that only use insulating Al2O3 as spacer layer. As a result, a considerably higher PCE of up to 15.03% was achieved. |
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