Modification of Wide Gap PMMA to Small Gap PMMA/CeO ₂ Polymer-Composite for Efficient Opto-Electronic Applications

CeO2 nanoparticles prepared by sol–gel method were incorporated into PMMA matrix at different concentration to fabricate PMMA/CeO2 nanocomposites films by solution-casting at room temperature. XRD confirmed the cubic fluorite crystals of CeO2, with all characteristic peaks and the absence of impurity peaks, confirming phase-pure nanocrystal formation. A broad peak at 13.8° corresponds PMMA and confirms good dispersion and compatibility between the filler and polymer. FTIR spectroscopy revealed the presence of expected functional groups of PMMA and subtle peak shift due to CeO2 incorporation confirms the successful formation of PMMA/CeO2 nanocomposites. FESEM micrographs further confirm that, at lower CeO2 concentrations, the inorganic nanoparticles show a good dispersion within the organic polymer matrix with little to no agglomeration. In contrast, at higher CeO2 loadings, a noticeable nanoparticle agglomeration is observed. In the nanocomposites, increasing CeO2 content reduced the direct/indirect bandgap from 4.7/4.2 to 4.39/2.65 eV and increased the refractive index from 2.014 to 2.65. During nanocomposite formation, inorganic nanoparticles play an active role to modify electronic structure of the polymer-inorganic nanocomposites by introducing localized energy states of CeO2. Tunability in band gap, enhanced refractive index and near-UV absorption efficiency demonstrating the potential of PMMA/CeO2 are promising candidate to design advanced-sustainable light harvesting applications.