Synthesis, optical, and electrochemical properties of 4-fluorophenyl end-capped oligofluorenes

Abstract This paper presents a series of oligofluorenes mainly based on 9,9-bis(2-ethylhexyl)fluorene units whose rigid core has been extended with 4-fluorobenzene termini. Thermogravimetric analysis, differential scanning calorimetry, absorption spectra, photoluminescence spectra, and cyclic voltammograms are used to analyze the thermal, optical and electrochemical properties of these oligomers. Test results show that the absorption and emission spectra of all oligomers are succession red-shift and the bandgap becomes narrow as an extension of the π-conjugated system. The absorption/PL spectra of 4-fluorobenzene-terminaled oligomers are red-shifted compared to the hydrogen-terminated compounds. The highest occupied molecular orbital values also exhibit a similar change.