Gigantic enhancement of optoelectrical properties in polythiophene thin films via MoS2 nanosheet-induced aggregation and ordering

Abstract

Conducting polymers (CPs), such as poly(3,3-dialkylquarterthiophene) (PQT-12), are attractive candidates for flexible thin-film electronics due to their cost-effectiveness and mechanical flexibility. However, the industrial application of CPs is limited by poor crystallinity and disordered polymer chain orientation. Herein, we report the enhancement in optical, structural, and electronic properties of PQT-12 by incorporating MoS₂ nanosheets in the polymer matrix. The PQT-12/MoS₂ nanocomposite exhibits improved crystallinity, molecular ordering, and charge transport properties, as evidenced by enhanced UV-visible absorption, quenched photoluminescence, and increased coherence length in X-ray diffraction. The floating-film transfer method (FTM), a scalable technique for large-area film fabrication has been used for thin film deposition. The nanocomposite film reveals a more ordered nano-fibrillar network in atomic force microscopy images, which is crucial for efficient charge transport. The charge transport has been studied by fabricating organic field-effect transistors (OFETs) and Schottky diodes. The nanocomposite based OFETs have shown mobility up to 3.6 × 10⁻³ cm V⁻¹ s⁻¹ with an on/off ratio of 10⁴, while Schottky diodes exhibit enhanced ideality factor, rectification ratio, and barrier height. These improvements are attributed to charge transfer interactions and enhanced polymer chain alignment induced by MoS₂ nanosheets, demonstrating their potential for high-performance flexible electronics.