Visible Luminescence of Dedoped DBU-Treated PEDOT:PSS
Films
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Abstract
Dedoping
of PEDOT:PSS by a simple and physical process has been
performed by the addition of 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU), a strong organic base, in the PEDOT:PSS aqueous dispersion.
The DBU-treated PEDOT:PSS samples showed a strong absorption band
at 600 nm (π–π* transition) and a small band at
900 nm (polaronic band), which indicates that some PEDOT chains were
being reduced. The dedoping efficiency depended of the amount of DBU
added to the aqueous PEDOT:PSS dispersion. The DBU-treated PEDOT:PSS
aqueous dispersions and films showed a strong yellow emission, visible
with the naked eye, when they were excited with a 488 nm laser. In
addition, the same emission features were observed using another reducing
agent like sodium hydroxide (NaOH), which indicates that the emission
originates from neutral PEDOT chains rather than artifacts. Finally,
Raman and FTIR spectroscopies were used to figure out the mechanism
responsible for the PEDOT reduction. The reduction of PEDOT chains
is due to the formation of hydroxide anions, which come from the interaction
of DBU with water present in the PEDOT:PSS aqueous solution and interact
with the oxidized thiophene molecules, resulting in a neutralization
of the PEDOT backbone