Easy synthesis of organic–inorganic hybrid nanomaterials: study of DC conduction mechanism for light dependent resistors

Abstract

A surfactant assisted chemical oxidation method has been employed for facial synthesis of polypyrrole/tin oxide (PPy/SnO₂) hybrid nanoneedles. The charge transport properties of the prepared hybrid nanomaterials have been analyzed under different conduction mechanisms for their possible application for light dependent resistors (LDRs). The scanning electron microscopy studies revealed that the increased concentration of additive SnO₂ quantum dots alters the surface morphology from nanowall-like to nanoneedle-like and the formation of PPy/SnO₂ nanocomposites is confirmed X-ray diffraction studies. The strong coupling between the PPy and SnO₂ results in the transformation of PPy from highly oxidized states to oxidized states and is confirmed through Raman analysis. The simple band conduction model and Kivelson's power law based conduction mechanism could not be applied to explain the conduction mechanism due to different reasons. The log σ_dc curves for all samples were well fitted for γ = 1/4, suggesting the applicability of Mott's three dimensional variable range hopping VRH model for charge transport. The room temperature dark conductivity of the samples was found to decrease with an increase in SnO₂ concentration. The formation of p–n junctions between p-type PPy and n-type SnO₂ changes the bandgap of PPy and the work function. This modifies the electronic structure of PPy which brings a synergistic effect in the photosensitivity of the PPy/SnO₂ nanocomposites. The room temperature photoresponse of the PPy/SnO₂ samples was found to increase from 2.85 to 6.25% at 100 mW cm⁻² illumination intensity with an increase in the SnO₂ doping concentration from 0 to 20%.