In this work, the thin films of β-phase poly(9,9-dioctylfluorene) (PFO) were realized using 1,2-dichloroethane as solvent. The absorption and photoluminescence spectra show an additional absorption peak at 435 nm and a red-shifted emission band, which indicates the formation of β-phase in the film. Polymer light-emitting devices based on thin films of β-phase PFO were fabricated. Device with β-phase exhibits efficiency of up to 3.43 cd/A that is 3.7 times higher than that of the device with amorphous phase. Furthermore, the device with β-phase emission has obvious advantages such as stable deep blue emission and high color purity over amorphous-phase device.

Clarifi cation of the solvent effects of bulky π -conjugated polymers on the conformation behavior and morphology evolution of the chain from solution to thin fi lm is the main prerequisite for the molecular design of printable polymer light-emitting materials. Here, three bulky poly(9,9-diarylfl uorene)s (PFs) with the steric hindrance effect are synthesized to examine gelation behaviors, β-phase conformation, fi lm 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(spirofl uorenexanthene)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.

Thin films of β-phase poly(9,9-dioctylfluorene) (PFO) were realized by dipping amorphous-phase PFO thin films in 1,2-dichloroethane for several seconds. Absorption, photoluminescence, and electroluminescence spectra indicate that the β-phase is generated in the thin films. A stable pure-blue polymer light-emitting device based on the β-phase PFO film was fabricated. The efficiency of the device with the β-phase is increased to 2.53 cd/A, which is 3.3 times higher than that of the device with the amorphous phase. Moreover, it is found that the device with β-phase emission shows high color purity as well as stable spectra.

Designing optoelectronic properties using heteroatomic conjugated polymers (HCPs).