Increase in dye-loading amounts and photovoltaic performance of dye-sensitized solar cells with the aid of electrostatic force

Abstract

An electrostatic attraction method was applied to reduce the dye-adsorption time in the fabrication of dye-sensitized solar cells (DSCs). Lead cations (LCs) were first deposited onto the surfaces of TiO₂ electrodes, and then, the electrodes were sensitized with Z907 dyes. Owing to the electrostatic attraction between the positive charges on the TiO₂ surfaces and the carboxylate anions (–COO⁻) in the Z907 dye molecules, more dyes were adsorbed onto the LC-deposited TiO₂ surfaces, which required only 1 h for dyeing, than in a reference TiO₂ electrode that was dyed for 4 h. Only-1-h-sensitized cells prepared from the LC-deposited TiO₂ electrodes showed higher power conversion efficiencies (PCEs) than 4-h-sensitized devices, which were fabricated using pristine TiO₂ electrodes without LCs. A higher dye-loading amount in the 1-h-sensitized cells led to retardation in the back electron transfer, and an enhancement in both light harvesting and electron collection efficiencies. These induced an enhancement in both the open-circuit voltage and short-circuit current in the 1-h-sensitized cells, compared to those of the reference cells. The electrostatic attraction method by the deposition of LCs could lead to an improvement in the PCEs of DSCs as well as a significant reduction in the dye-adsorption time.