Ultrafast photoexcitation dynamics behavior of hydrogen-bonded polyfluorenol

Abstract

Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer (LCPs) for optoelectronic devices. Singlet excitons are easily trapped by the intrinsically defect structures. Herein, we set a polyfluorenol (PPFOH) as an example to systematically investigate its photophysical behavior to check the role of defect structures in LCPs. According to time-resolved photoluminescence analysis, the feature emission peaks from individual chain of PPFOH in diluted DMF solution is effectively avoided the influence of fluorenone formation, but the residual green-band emission at 550 nm is easily observed in the PL spectra of PPFOH dilute toluene solution obtained delay 1.5 ns, confirmed the formation of “guest” physical aggregation-induced defect structure. Remarkably, efficient and ultrafast energy transfer from individual chain to defect structure is observed in PPFOH films. Interestingly, the efficient energy transfer happened for the film obtained from DMF solution (200 ps) than those of toluene ones (600 ps). Meanwhile, compared to relatively stable green-band emission in PPFOH film from toluene solution, red-shifted emission peak (11 nm) of PPFOH film from DMF solutions exposed to saturated DNT vapor also confirmed their different aggregation-induced green-band emission. Therefore, this aggregation defect structures are influenced on the photophysical property of LCPs in solid states.