Pyrenyl-Capped Benzofiurene Derivatives: Synthesis, Characterization, and the Effects of Flexible Side Chains on Modulating the Optoelectronic Properties

A new series of pyrenyl-capped benzofiurene derivatives (PFP-1, PFP-2, PFP-3, and PFP-4) were designed, synthesized, and investigated as model compounds for understanding the effects of flexible side chains on modulating the functional properties of organic semiconductors for optoelectronics. The resulting compounds exhibited high fluorescence yields (changing from 28% for PFP-1 to 46% for PFP-3), good thermal stability (increasing from 439 °C for PFP-4 to 510 °C for PFP-1), and fair glass-transition temperatures (ranging from 84 °C for PFP-4 to 175 °C for PFP-1). According to ultraviolet absorption (UV) and photoluminescence (PL) spectra, the long flexible side chains on diaryl substituents have played an important role on influencing the intermolecular interactions and radiative deactivation decays. Moreover, the flexible side chains on diaryl substituents also influence the process of exciton migration and exciton quenching, further resulting in different photoluminescence quantum yield (PLQY) and tran...