De-aggregation of polyfluorene derivative by blending with a series of poly(alkyl methacrylate)s with varying sidegroup sizes

Polyfluorene based blends for white light emission

“…Its fluorescence emission is much broader than that in solution with the 0-0 band at k em(0-0) = 487 nm, red-shifted by 15 nm compared to the dilute solution. In addition, two other strong bands at 517.8 and 551.6 nm are observed, possibly originated from aggregates [41]. Further, the LaPPS16 aggregate emission has a greater contribution to its total emission than that observed for LaPPS10.…”

“…The LaPPS10 absorption band is broad and centered at k abs = 394 nm, red-shifted by 16 nm compared to the dilute solution. The presence of the low intensity band at k abs = 432 nm is a strong evidence that during the film formation some chains or chains segments are arranged in the b-conformation, a more planar orientation of the backbone [36,[38][39][40][41]. The differences in the emission spectra of the blue emitter LaPPS10 in solution and in film form give further support for the presence of the b phase.…”

“…That could be in part responsible for the absence of the higher energy bands seen in dilute conditions. The additional red-edge emission band at k em = 534 nm is characteristic of the LaPPS10 aggregates [41].…”

Photo- and electroluminescence in a series of PPV type terpolymers containing fluorene, thiophene and phenylene units

“…Additionally no signal was seen either in the FTIR or in RMN spectra that could be ascribed to any kind of chemical alteration. This second longer component was thus attributed to interacting chains, since there are several indications that LaPPS30-0 can easily undergo aggregation even in relatively low concentrated solutions [26,27], as noted. The PL decay of LaPPS30-100 is monoexponential with PL = 1.18 ± 0.03 ns when the signal is collected at em = 550 nm (emission peak).…”

“…When in solid state, in addition to the intrachain energy transfer and charge transfer processes, interchain photophysical processes also play important roles due the possibility of polymer aggregation, a very common process in both polyfluorenes and polythiophenes [18][19][20][21][22][23][24][25][26][27]. In photoluminescence (PL), along with the emission of isolated chains, emission of aggregates may be possible in some cases, whereas in others the quenching of the emission is the most important process.…”