Three novel polysulfide-based conjugated polymers and characterization of their optoelectronic properties

Abstract

The aim of this study was to investigate the effect of side chain size on the optical and charge transport properties of thin films prepared from novel conjugated polysulfide-based polymers. Three polymers, labeled P1, P2, and P3, were derived from polysulfide derivatives and had different arylene groups (5,5′- biphenylene, 4,4′-biphenylene, and 2,6-pyridylene). Optical analysis was performed using photoluminescence (PL) and UV–visible absorption spectroscopy, revealing an energy band gap of 2.41–3.02 eV; P1 emitted yellow, P2 blue-green, and P3 green. Cyclic voltammetry measurements of the electrochemical band gap and HOMO and LUMO energy levels revealed that the polymer exhibited p-type semiconductor activity; the electrical properties of diodes based on the ITO/polysulfide derivative/Al structure were explored through analysis of current-voltage characteristics. The current space charge limitation (SCLC) mechanism was used to model the behavior of these diodes; the P2 thin film layer exhibited higher mobility than the other layers. The relationship between the geometry of the polymer thin films and their optical and electrical properties was thoroughly investigated.

Keywords

• Conjugated polymers
• Impedance spectroscopy
• Current-voltage (SCLC)
• UV–Vis absorption
• Polysulfide compounds