Effect of carbon nano-dots (CNDs) on structural and optical properties of PMMA polymer composite

In this report direct band gap polymer composites with amorphous structure were fabricated which are important for applications in optoelectronic devices. Solution cast technique has been used for the preparation of polymethyl methacrylate (PMMA)/carbon nanodots (CNDs) nanocomposite films. The Fourier-transform infrared spectroscopy (FTIR) outcomes display the occurrence of complexation between PMMA and CNDs. The analysis of X-ray diffraction (XRD) shows an improvement of amorphous phase of PMMA with CNDs addition. The surface morphology of the films was examined by means field emission scanning electron microscopy (FESEM) technique. CNDs are formed and distributed in the FESEM composite image. Photoluminescence (PL) spectroscopy study showed that the PMMA/CNDs nanocomposite film emission is dominated by a broad-band around 480 nm, exhibiting a well-defined excitonic emission feature. From Ultraviolet–visible (UV–Vis) spectroscopy study, the optical band gaps of pure PMMA and PMMA/CNDs nanocomposite films were calculated. The dispersion behaviour of the refractive index of PMMA was shifted to higher wavelength upon doping with CNDs. The optical dielectric loss was used to specify the most probable electron transition type. Due to the enhancement of the UV–Vis absorption and photoluminescence behaviour, this nanocomposite film could be considered as a promising candidate to be used in future nanotechnology-based devices. Keywords: PMMA polymer nanocomposite, XRD and FTIR study, FESEM, Photoluminescence, Carbon nanodots, Optical properties