Abstract
We present our findings on the preparation, UV photoresponse of nanocomposite films(NCF) on a flexible substrate consisting of orthorhombic molybdenum oxide (α −MoO3) and the conducting polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS). We also studied the nonlinear optical properties of prepared NCF on glass substrate. The pristine MoO3 was synthesized using a direct precipitation method which is followed by annealing to ensure the formation of high quality orthorhombic MoO3. MoO3/PEDOT:PSS nanocomposite films with varying MoO3 concentrations were fabricated and employed in photodetector devices to investigate the influence of MoO3 content on photoresponse behaviour. Comprehensive structural investigations were conducted using X-ray diffraction (XRD), revealing minor variations in structural parameters like crystallite size, microstrain, and dislocation density, indicative of the interaction between MoO3 and the polymer matrix. Scanning electron microscopy (SEM) provided detailed insights into the morphological characteristics, showing uniform distribution. UV–visible (UV–vis) spectroscopy demonstrated bandgap variations correlated with the MoO3 concentration in the nanocomposites, highlighting the tunability of optical properties through compositional adjustments. Fourier-transform infrared (FTIR) spectroscopy elucidated the vibrational properties of the nanocomposites, confirming the successful incorporation of MoO3 within the polymer matrix and its impact on vibrational modes. The fabricated photodetectors exhibited a negative photoresponse at low MoO3 concentrations, characterized by a decrease in current under UV illumination, indicative of unique charge trapping and recombination mechanisms. However, as the concentration of MoO3 in the nanocomposite increased, the photoresponse transitioned to a positive mode, reflecting a decrease in resistance upon UV exposure. This tunable photoresponse behaviour underscores the potential of MoO3/PEDOT:PSS nanocomposites for flexible UV photodetector applications. Nonlinear optical studies show the enhanced saturable absorption in NCFs. These findings underscore the significant saturable absorption properties and negative photoresponse, indicating promising avenues for further investigation into the photoresponse and nonlinear optical characteristics of NCFs.
Published Version
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