Substituent position effects on blue light emission of organophosphonium organic compounds for potential OLED applications

Blue light-emitting materials are crucial for the commercialization of OLEDs, especially in dark display applications. However, a comprehensive understanding of the relationship between blue light emission and material structure remains lacking. In this study, we synthesized three organic phosphonium salts with blue light emissions using a one-step methylation method. The correlation between molecular structure and light emission was investigated, revealing that the position of the methyl group on the benzene ring introduces varying degrees of steric hindrance, which in turn affects the spatial arrangement and energy level distribution of the compounds. This research paves a significant development in blue light-emitting materials for future OLEDs and facilitates the commercialization of organic phosphonium cationic salts. Moreover, the usage of the position isomerization of methylated organophosphorus salts can achieve stereoscopic controlled blue emissions, providing a low-cost alternative to precious metal-based systems.