Poly(ionic liquid) Bridge Joining Smectic Lamellar Conducting Channels in Photoelectrochemical Devices as High-Performance Solid-State Electrolytes

• Published in: ACS applied energy materials Vol. 4; no. 9; pp. 9479 - 9486
• Main Authors: Wang, Caihong, Li, Xueyong, Zhou, Jiwen, Tian, Wen, Ji, Junyi, Wu, Yong, Tan, Shuai
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.09.2021
• Subjects: smectic liquid crystal; poly(ionic liquid); microphase-segregation nanostructure; dye-sensitized solar cells; solid-state electrolyte
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.1c01670

Nanostructured ionic liquid crystals have emerged as promising electrolytes with the potential to satisfy the demands of both efficient charge transport and stability over conventional liquid electrolytes for advanced energy devices. However, traditional methods via the macroscopic orientation of ionic liquid crystals for charge transport intensification can hardly be achieved during practical device applications. Herein, a simple method was proposed to spontaneously construct long-range continuous conducting channels for significantly improving the charge transport of ionic liquid crystals in the confined space of energy devices. A poly­(imidazolium ionic liquid) was designed and in situ prepared in a smectic [C14MIm]­[I]-based electrolyte for photoelectrochemical device fabrication. The composite solid-state electrolyte self-assembled microphase-segregation nanostructures, wherein the poly­(ionic liquid) aggregated at the boundaries of layered smectic polydomains. The imidazolium iodide ions in the poly­(ionic liquid) acted as imbedded ion tunnels at domain interfaces via π–π stacking and ionic interaction, which facilitated the charge transport crossing the interfacial gaps to join the intradomain lamellar channels as thermally stable and long-range continuous charge transport pathways. By using the poly­(ionic liquid) to bridge the domain-interfacial gaps, the ion conductivity of the ionic liquid crystals was up to 7 times increased with a maximum value of 2.0 × 10–3 S cm–1, and the derived dye-sensitized solar cell could operate stably at 70 °C with a 2-times enhancement and champion efficiency of 8.2%. The approach here was comparable but more processable to traditional methods via the macroscopical orientation of ionic liquid crystals for charge transport intensification within energy devices, which have great potential to develop high-performance solid-state electrolytes to achieve the best balance between efficiency and durability for energy devices.