Progress in optoelectronic applications of ionic liquids

Optoelectronic device technology is the future advancement of electronic industry. The practical application of photovoltaic devices or light-emitting devices has already been stepped up in the market. The optoelectronics mainly find their applications as an energy conversion device. They are used to convert light to electricity or emit light. With the growing need of energy conversion devices, the search for renewable and environment friendly sources of energy is rising. The dye-sensitized solar cells (DSSCs) are the next-generation solar cells that convert solar light energy into electricity with simple device fabrication and at reasonable cost. The DSSCs have attained considerable attention due to the high photon to electrical energy conversion, ease in fabrication at reasonable cost, efficient for indoor energy supply, and an alternative source for clean energy. However, traditional DSSCs have been challenged because of the use of organic solvents as an electrolyte, which causes severe environmental issues. Ionic liquids (ILs) with the excellent properties have the potential for variety of energy-related different applications. To eliminate organic solvents, polymer-based ILs, Poly (ILs) (PILs), have shown great potential to show improvement in cell efficiency and durability. The ILs improve the ionic conductivity by promoting redox ion species (iodide/triiodide) within an electrolyte. This chapter briefly reviews the role of different PILs used as an electrolyte and how the ionic conductivity has been effected by iodide species for solid–state/quasi-solid–state DSSCs.