Solvent and steric hindrance effects of bulky poly(9,9-diarylfluorene)s on conformation, gelation, morphology, and electroluminescence

Clarification of the solvent effects of bulky π-conjugated polymers on the conformation behavior and morphology evolution of the chain from solution to thin film is the main prerequisite for the molecular design of printable polymer light-emitting materials. Here, three bulky poly(9,9-diarylfluorene)s (PFs) with the steric hindrance effect are synthesized to examine gelation behaviors, β-phase conformation, film morphology, and electroluminescence (EL) spectra in three solvents. Their gelation behaviors occur in 1,2-dichloroethane (DCE) of high concentrations, featuring emission bands of ≈470 nm as well as the β-phase conformation. Bulky PFs also exhibit different solvent effects on the morphology and green emission bands. Compared with other bulky PFs, poly(spirofluorenexanthene)s have obvious advantages in terms of the solvent-independent emission, high quantum yield, and air-stable photoluminescence, as well as the EL spectra. Poly(SFX) will be potential components for the formula of optical inks in printed electronics. The evolution from solution to film of bulky poly(9,9-diarylfluorene)s (PFs) is studied. The gelation behaviors that are demonstrated in 1,2-dichloroethane (DCE) solutions feature emission of 470 nm, and β-phase. Obvious solvent and steric hindrance effects happen in the morphology in annealing thin films and g-band in photoluminescence (PL) and electroluminescence (EL), demonstrating that the less solvent effects, the more stable the chain conformation and morphology.