Insulating -conducting polymer blends exhibit fascinating optical properties. Poly [2-methoxy-5(3’, 7’- dimethyloctyloxy)-1, 4- phenylenevinylene] [MDMO-PPV] is a widely used conducting polymer with band gap of about 2eV. The thin films of MDMO-PPV prepared from chloroform has the absorption maximum at about 490nm and emission maximum at around 590nm. We have prepared free standing films of MDMO-PPV doped at 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% and 3.0wt % of 1:1 PMMA/PVAc non conducting polymer matrix by solution cast method. Absorption peaks are slowly red shifted from 499.4nm for 0.5 wt% sample to about 514.2nm for 3.0 wt% sample. Red shift is also observed in emission spectrum (fluorescence spectrum) ranging from 586nm to about 593nm with the increased doping level. Considerable Stoke’s shift has been noticed which plays an important role inhibiting fluorescence quenching. New material exhibits multiband gap structure that are calculated using Tauc’s plot. Least direct band gap of 1.93 eV and indirect band gap of about 1.27eV are noticed. Thermogravimetric and Differential Scanning calorimetry affirmed slight variations in the stability of the samples compared to that of pure PMMA/PVAc films. There is no such drastic change in the thermal stability, may be because of very small variation in the doping concentrations. Observed broad band absorption and also efficient emission in the visible region along with the tailored absorption -emission properties can be used in the designing a new materials of desired properties.

Poly(3-hexylthiophene-2,5-dyil) (P3HT) doped Polymethyl methacrylate (PMMA) free standing films are prepared by solution cast method. Weight ratios are maintained at very low concentrations of the dopant in the range 0.001wt% to a maximum of 0.7wt%. UV-Visible ,Fluorescence, AC conductivities and Xray diffraction studies are carried out. A multi band gap material with band gaps in the ranges of 4.5 to 5eV, 4 to 4.5 eV, 3 to 3.5eV and 1.5 to 2eV have been noticed. PMMA being an insulating matrix turns out to be a conducting material with the insertion of highly conjugate P3HT polymer. Fluorescence excited by 375nm at room temperatureaffirmed no drastic changes in the emission property of P3HT inside PMMA environment. There is increase in ac electrical conductivity, dielectric constant as expected. XRD diffractograms revealed diffused diffraction bands indicating the polycrystalline nature of the new material. Transparent polymer films can be used in theconstruction of solar cells, LEDs, display systems and even as a transparent electrode.