Dye and quantum dot (QD) are representative sensitizers of the photochemical solar cells. Dye has the highest efficiency in the whole sensitizers. QDs have relatively low performance but their multiple exciton generation enhanced theoretical efficiency from 33 to 44% and expected to achieve high efficiency. This work tried to enhance the photovoltaic performance with the co-sensitization of N719 dye and Si QD. The performance of dye and QD co-sensitized solar cell was not much enhanced because of electron loss of charge recombination. Therefore, TiO2 barrier layer was introduced on TiO2 and Si QD. It blocked the charge recombination with redox electrolyte. It also helped better electron injection from excited dye to TiO2 with strengthened dye adsorption. Consequently, the performance of co-sensitized solar cell was enhanced with reduced charge recombination and increased dye adsorption.