Estudo do comportamento fotofísico de polímeros conjugados derivados de fluorenos através de espectroscopia linear a não-linear ultrarrápida

Abstract

A detailed study of the photo physical properties of polymers based on fluorine’s derivative is performed through ultrafast nonlinear spectroscopy. The polymer chains are studied in solution, where absorption and emission occur from a disordered distribution of isolated chains, and in solid state as a film, where interchain interactions promote efficient energy transfer. Coherent photoexcitation produces delocalized excitons, which relax and localize on the lowest energy chromophores on the polymer chains on a 100 fs timescale. This is revealed by ultrafast transient absorption spectral evolution, anisotropy relaxation and excited state specific high time resolution fluorescence spectroscopy. The photophysical behavior of the polymer in solution and as a film is significantly different indicating that there is not a significant amount of selfcollapsed chain conformations in solution. Compared to solution, in the film, the excited state relaxes an order of magnitude faster, indicating that interchain interactions are strong, promoting efficient energy transfer. The timescales of exciton dynamics revealed in this study are important for further theoretical modeling of these polymer structures and when designing blends for use in optoelectronic and electro-optical devices.