Protonation and charge transfer in polyaniline: an optical absorption study of the mixed solutions

Interaction of polyaniline (PANI) with a protonating dopant, dodecylbenzenesulfonic acid (DBSA), and an organic electron acceptor, pentadecyltetracyanoquinodimethane (C15TCNQ), is studied in DMSO solutions, using optical absorption spectroscopy. Each of the two agents alone induces an absorption band at 417 nm, attributable to cation-radicals of PANI. Free carrier absorbance in the near-infrared is absent in the case of C15TCNQ. Moreover, the charge-transfer interaction between PANI and C15TCNQ suppresses a transition to the conductive state. When PANI/C15TCNQ mixtures are aged, a new band near 500 nm appears that can be attributed to an adduct of PANI and C15TCNQ.