A simple and effective crystal growth inhibitor for high performance solid-state dye-sensitized solar cells

Abstract

Three simple imidazolium-type ionic liquids with benzene cores (abbreviated as [TMImB][Br] and [TMImB][TFSI]) have been successfully designed, synthesized and characterized. The chemical structure, thermal and electrochemical properties have also been investigated in detail. Moreover, it is revealed that adding 20 wt% [TMImB][TFSI] could effectively suppress the crystal growth of the typical ionic conductor 1-ethyl-3-methylimidazolium iodide (EMII). Meanwhile, [TMImB][TFSI] can facilitate the EMII-based solid-state electrolyte to form a much smoother surface morphology than EMII alone, which can improve interfacial electrochemical contact among EMII and porous TiO₂ films. Therefore, the resultant solid-state DSSC with [TMImB][TFSI] exhibits a higher efficiency of 5.66% than the DSSC without crystal growth inhibitors, and displays better long-term stability than the DSSC with conventional EMIBF₄. These preliminary results provide us with more opportunities to explore new crystal growth inhibitors with special chemical structures for high performance ssDSSCs.