PMMA–TiO2 based polymeric nanocomposite material for electron transport layer in OLED application

Abstract

Nano sized polymer embedded inorganic metal oxide nanocomposites consisting of PMMA–TiO2 were synthesized via free radical polymerization of methyl methacrylate. Their structural, optical, thermal, electrical and electrochemical properties were examined. Aggregated irregular tetragonal bipyramidal structural of TiO2 nanoparticle were embedded on the spherical ball like structure of PMMA. The in-depth topological images were examined by transmission electron microscopy and it was well agreement with field emission scanning electron microscopic images. The corresponding changes in nano strain and bond length with the incorporation of TiO2 nanoparticle in PMMA matrix were observed by X-ray diffraction technique and Fourier transform infrared spectroscopic spectroscopy. The FT-Raman spectra confirmed the anatase phase of titania in PMMA–TiO2 nanocomposite. The PL spectra for PMMA–TiO2 nanocomposite showed four bands attributed to blue-violet band, blue band, green band, yellow band respectively and its color coordinate was observed to be in blue region. The shifting of transmittance edge for PMMA–TiO2 towards blue region was in good agreement with the result of CIE diagram with better thermal stability. Optimized reduced band gap (~ 2.93 eV) and enhanced current density (~ 110%) were calculated which led to improvement in conductivity for PMMA–TiO2 nanocomposite. The dielectric properties of PMMA–TiO2 nanocomposite showed high dielectric constant with meager dielectric loss. The electrochemical measurement confirmed the better specific capacitance with high conductivity for PMMA–TiO2 nanocomposite and enhanced the electron transport properties. Such a better thermal stability, reduced optical band gap, high dielectric constant, higher non radiative recombination rate as well as p-type conductivity concluded that it can be used as electron transport layer in OLED devices.