A low molecular mass organogelator electrolyte with TiO₂ nanoparticles for stable and efficient quasi-solid-state dye sensitized solar cells

We report stable and efficient quasi-solid-state dye-sensitized solar cells (QS-DSSCs) fabricated using a combination of TiO₂ nanoparticles and a low-molecular-mass organogelator (LMOG) as a nanoparticle-gel composite electrolyte. Three types of electrolyte, namely liquid, LMOG-based gel, and nanoparticle-gel composite, are used. The results of electrochemical impedance spectroscopy and intensity-modulated photocurrent/photovoltage spectroscopy measurements suggest that the presence of TiO₂ nanoparticles in the nanoparticle-gel composite electrolyte could afford faster electron transport and a longer electron recombination time compared to the liquid and LMOG-based gel electrolytes. The QS-DSSC using the nanoparticle-gel composite electrolyte with the optimal TiO₂ content exhibits a power conversion efficiency of 7.79%, which is significantly higher than that of devices using the liquid (7.22%) and LMOG-based gel (7.21%) electrolytes. Remarkably, the QS-DSSCs with the optimal nanoparticle-gel composite electrolyte exhibit long-term stability over 10 days, unlike the liquid electrolyte-based cells.