Efficient and stable deep blue polymer light-emitting devices based on β-phase poly(9,9-dioctylfluorene)

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.