Exciton Dynamics and Nonlinear Optical Properties of Semiconductor Polymer Nanocomposites

Abstract

The numerous exciting characteristics and immense application opportunities of two-dimensional (2D) materials have drawn significant and widespread interest in recent years. Thanks to the modulation of the band gap of 2D materials, transition metal dichalcogenides (TMDCs) may have more potential value than other semiconductor materials. Excitons, a fundamental excitation in condensed matter that may transmit energy without conveying net electric charge, are generated when photons excite these materials. Compared with traditional photonic materials, constructing heterostructures with different 2D semiconductors and optically active polymers has attracted significant interest due to their diverse electronic properties and effective separation of charge carriers. These novel nanocomposites also allow for the tunning of photocarrier efficiency, which leads to strong excitonic interaction, thus making such devices suitable for LEDs, photomarkers, and other related photonic applications. newlineHowever, in this thesis, by focusing our attention to explore the correlation between the excitonic behavior and the charge transfer in the semiconductor/polymer nanocomposites, we have carried out the synthesis of different semiconductors including ZnO NRs, MoS2 nanosheets, different conducting polymers including PANI, PPy, etc. and their composites by using low cost, environment-friendly chemical method. Several characterization tools have been used to analyze the structure and morphology of the synthesized nanomaterials. newlineIn brief, we have demonstrated the synthesis of ZnO nanorods by sol-gel technique and their composites with PEDOT:PSS by the solution-casting method. The optical properties have been studied to investigate the dynamics of charge carriers in the composites. The optical nonlinearity was also measured by the open aperture z-scan method and the composite samples show saturable absorption behavior caused by ground state bleaching.