Organic photovoltaic cell is the most promising one in the third generation solar cell. Considering the materials used for fabricating devices, it generally can be classified as two sorts. One is called full organic solar cell, which is all made by organic or polymeric molecules. The examples of this type of solar cell includes bulk heterojunction solar cell (BHJ solar cell). Another one is organic/inorganic hybrid solar cell, and most of them are composed of organic-inorganic blends. For instance, solid state dye sensitized solar cell (ss-DSSC) is made by porous dye-coated inorganic semiconductor and then infiltrating organic conductor into it. One of the most commonly-used organic hole conductor is spiro-MeOTAD (2, 2', 7, 7' -tetrakis (N, N-di-p-methoxyphenylamine) 9, 9'-spirobifluorene). The ss-DSSC made by spiro-MeOTAD already reached an average power conversion efficiency around 3-4% and a record efficiency of 7.2% from Gratzel's group. However it is still below a desired level for manufacturing usage. This dissertation presents three approaches to optimize the ss-DSSC: Increasing fill factor in ss-DSSC, enhancement of light harvesting and In the first part, we first provide an overview of doping in organic or polymeric materials. Subsequently, we discuss the prior literature on p-dopants and additives incorporated into ss-DSSCs. Finally we present our data that suggests the primary role of Lithium salts is to stabilize the oxidized state of the hole conductorIn the second part, we use surface-initiated polymerization to anchor hole conducting polymers onto silica nanoparticles. We argue that the formation of silica/polymer composites serve as a light scattering layer on the top of photoanode, raising the short circuit current by 26% over conventional spiro-MeOTAD ss-DSSCsFinally, a simple strategy is presented which effectively increases the pore-filling fraction of spiro-MeOTAD into photoanode. Heating the cell during the fabrication process lowers the electrolyte viscosity and surface tension, enabling an 86% increase in cell efficiency over cells without heat treatment.
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