Enhancing Electron Transport in Polyfluorene-Based PLEDs: The Role of Polystyrene Blending on <i><b>β</b></i>-Phase Formation and Phase Separation

To enhance the charge transport performance of poly(9,9-di-n-octylfluorene) (PFO) in polymer light-emitting diodes (PLEDs), the electron transport behaviors of PFO blended with polystyrene (PSt) were investigated. Electron-only (EO) devices were fabricated using a solution process to assess electron transport performance. The results demonstrated that blending PFO with a minority of PSt induced β-phase formation and phase separation upon annealing, contributing to improved electron transport properties. EO measurements revealed that the electron mobility of PFO/PSt blends (PSt: 30wt%, 40%) after annealing was higher than that of pure PFO in both states.