Azobenzene-dyed, nanofibrous microstructure for improving photothermal effect of polymer gel electrolyte

Insufficient ion capacity from a room temperature polymer electrolyte is commonly a short slab of the solid-state photoelectrochemical systems, like solid-state dye-sensitized solar cells (S-DSSCs). To overcome this drawback, herein a facile strategy based on the light-induced temperature-rise effect on the electrolyte has been given. By applying a photo-heatable, well-nanostructured polymer electrolyte dyed with azobenzene, it is found that the azobenzene can remarkably increase the ion conductivity of the gel electrolyte, and obtain better light-harvesting efficiency. To explore the mechanism, differential scanning calorimeter and infrared imaging system are used to accurately evaluate the temperature rise of such electrolyte under different preparation or irradiation conditions. It shows that significant photothermal heating effect on the electrolyte can both benefit from the incorporated azobenzene as a "micro solar-heater" and the rich nanostructure of the matrix surface that increases the area of interaction with light. Under standard sunlight, the azobenzene-stained polymer electrolyte can obtain a temperature rise from 1.2 degrees C (no staining) to 9 degrees C (dyeing), and the corresponding ionic conductivity increases up to about 40%. Accordingly, the photothermal photo-to-electron conversion efficiency of S-DSSC is significantly improved by ~50%.