Carbon black/silicon nitride nanocomposites as high-efficiency counter electrodes for dye-sensitized solar cells

Abstract

A carbon black–silicon nitride (CB–Si₃N₄) nanocomposite is prepared as a cost-effective counter electrode (CE) for dye-sensitized solar cells (DSSCs). The CB–Si₃N₄ nanocomposite is coated on an FTO substrate via the screen printing method. The results demonstrate that when the thickness is fixed at 4.7 μm the CB–Si₃N₄ composite CE exhibits lower charge transfer resistance and higher electrocatalytic activity towards the reduction of tri-iodide over the CB and Si₃N₄ electrodes. The CB–Si₃N₄-3% CE achieves the best catalytic activity and the prepared DSSC shows a power conversion efficiency of 8.06%. As the thickness of the CB–Si₃N₄-3% CE increases, the electrocatalytic ability is enhanced, and the charge transfer resistance at the electrolyte/CE interface decreases. The overall performance of the CB–Si₃N₄-3% CE with a thickness of 14.1 μm is comparable to that of Pt-doped CEs. Furthermore, a DSSC equipped with CB–Si₃N₄-3% CEs of 14.1 μm thickness exhibits a high efficiency of 8.37%, which is comparable to that of the Pt-based DSSC (8.50%). The simple preparation technique, outstanding electrocatalytic activity, and low cost of production allow the CB–Si₃N₄ nanocomposite to be a promising and efficient CE for DSSCs.