Morphology, Photoexcitation Dynamics and Stability of Water-Dispersed Nanoparticle Films based on Semiconducting Copolymer

Abstract

Water dispersed nanoparticles from the poly [2,7- (9,9-dioctyl dibenzosylole) -alt-4,7-bis (thiophen-2-yl) benzo-2,1-thiadiazole] copolymer (PSiF-DBT) were synthesized using the colloidal mini-emulsion technique. This dispersion was used to prepare thin films by spin coating making it possible to compare with similar films obtained using organic solvents. The absorption measurements pointed that the band gap of the nanoparticle thin film remain unchanged, while steady state and time resolved photoluminescent measurements presented a difference in the mechanism of relaxation processes. Through photoexcitation dynamics, it was observed that there is a difference in the electronic transition time due to the material morphology. Nanoparticles with the dimensions 50 nm were produced, and morphological analyses presented a film with good substrate coverage and nanoparticles with spherical shapes. Near edge X-ray absorption fine structure, X-ray photoemission and resonant Auger spectroscopies were employed to investigate nanoparticle films electronic structure, degree of ordering, and charge transfer dynamics.