Abstract
Improving photophysical properties of poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene]-end capped with dimethylphenyl, MDMO-PPV-DMP, was achieved via incorporation anatase titania nanoparticles (TiO2 NPs). Various contents of TiO2 NPs (up to 50 wt%) were dispersed into fixed concentration of the MDMO-PPV-DMP (5 mg/mL) via solution blending method followed by spin coating onto cleaned glass substrates to form their thin films. The formation of MDMO-PPV-DMP/TiO2 nanocomposites was evidenced from the results of X-ray diffractograms and Fourier transform infrared spectra, while the homogeneity of the films was detected by field emission-scanning electron microscopy (FE-SEM). Increasing the contents of TiO2 NPs resulted in a slight decrease (up to similar to 0.07 eV) in both direct and indirect energy band gaps of the MDMO-PPV-DMP in the nanocomposite thin films. A higher degree of disorder in the electronic structure of the MDMO-PPV-DMP/TiO2 nanocomposite and increasing the localized states density within the forbidden gap can be achieved by increasing the energy tail values and decreasing the steepness parameter with rising the TiO2 NPs content. The enhancement in emission intensity and broadening of emission spectra with increasing the TiO2 NPs content can be explained by the charge trapping effect and particle size distribution, respectively. Moreover, the incorporation of TiO2 NPs into the MDMO-PPV-DMP led to tuning its emitted light color which is of distinct interest in optoelectronic devices.