A novel parallel configuration of dye-sensitized solar cells with double-sided anodic nanotube arrays

In dye-sensitized solar cells based on anodic titania nanotube arrays, the low photocurrent in the backside-illuminated configuration has hindered their development. To increase the energy absorption and thus promote the photocurrent, a novel parallel configuration of dye-sensitized solar cells is proposed and achieved in this work on the basis of double-sided anodic nanotubes. The parallel connection is verified by electrochemical impedance spectroscopy measurements. The parallel cells exhibit an average 70% increment in photocurrent and 30% enhancement in efficiency as compared to the single cells, due to significantly increased surface area and highly reduced series resistance. Theoretical calculation and experimental fitting results demonstrate that a tube length of ∼30 μm is optimal for the nanotubes used in this study with backside-illuminated architecture.