Thermostable succinonitrile-based gel electrolyte for efficient, long-life dye-sensitized solar cells

Succinonitrile, a molecular plastic crystal, can be modified to become gel by introducing the hydrogen bond (O-H center dot center dot center dot F) network upon addition of silica nanoparticles and 1-butyl-3-methylimidazolium tetrafluoroborate (BMI center dot BF4). The succinonitrile-BMI center dot BF4-silica gel system is thermostable over a wide temperature range. The gel electrolyte based on this system containing I- and I-3(-) is also thermostable and highly conductive (6.6-18.2 mS cm(-1)) in the measured temperature region (20-80 degrees C). The appropriate addition of silica nanoparticles and BMI center dot BF4 has no adverse effects on the mobility capability of I-/I-3(-) ions, and the absence of succinonitrile deteriorates the mobility capability. Importantly, dye-sensitized solar cells (DSSCs) with this gel electrolyte show solar-to-electric energy conversion efficiency of 5.0-5.3% over a wide temperature range (20-80 degrees C). Furthermore, the aging test reveals that the cell still maintains 93% of its initial value for the conversion efficiency after being stored at 60 degrees C for 1000 h, indicating an excellent long-time durability.