Used primarily in electrochromic devices, it serves as an electron transfer agent, enabling color changes when an electric current is applied. This property makes it valuable in smart windows, mirrors, and displays that adjust transparency or color based on electrical input. Additionally, it is employed in research for studying redox reactions and electron transfer processes due to its stable and reversible redox behavior. Its application extends to photochemical systems where it acts as a photosensitizer or quencher in energy transfer studies.