Probing the role of dopants on structural and electrical properties through Raman and Impedance spectroscopy in Poly (3-methylthiophene) devices

• Published in: Synthetic metals 2024-09, Vol.307, p.117643, Article 117643
• Main Authors: Usha, S.K., Shanbogh, Shobith M., Mandal, Sougata, Varade, Ashish, Anjaneyulu, P.
• Format: Article
• Language: English
• Subjects: Charge transport; Conjugated polymers; Electrochemical synthesis
• ISSN: 0379-6779
• DOI: 10.1016/j.synthmet.2024.117643

The dopants in the polymer play an important role in modulating the electrical conduction as well as structural and morphological properties. Probing and correlating these aspects through various experimental tools is an important study in polymer device physics. Here, an attempt is made to correlate the structural and electrical properties of poly (3-methylthiophene) (P3MT) based devices with three different dopants using current-voltage (I-V), Impedance and Raman spectroscopy measurements. Three P3MT thin films with different dopant ions, namely Hexafluorophosphate (PF6−),Tetrafluoroborate ( BF4−) and Perchlorate ( ClO4−) are grown onto stainless steel substrates by electrochemical method. The peaks in the Raman data indicate quinoid and aromatic like structures in all P3MT thin films. I-V and impedance measurements show that the device P3MT with LiClO4 exhibits dominant bulk conduction, whereas the other two devices, P3MT with TBAPF6 and P3MT with TBABF4 show the interface-related conduction. The Cole- Cole plots and Impedance data are analyzed using equivalent circuit model by simulation, consisting of two parallel RQ circuits in series. From the simulated data, a few device parameters are extracted. The Raman, I-V and impedance results are correlated to present a broad overview to understand the device physics. •Thin films of P3MT with three dopant ions such as PF6−, BF4− and ClO4− were grown on SS foil using electro-chemical method.•I-V and Impedance measurements show bulk conduction in ClO4− doped P3MT.•PF6− and BF4− doped P3MT show interface related conduction.•Disordered morphology is reflected for PF6− doped P3MT samples.•Raman peaks indicate quinoid and benzoic like structures in all P3MT thin films.