Light emission in phase separated conjugated and non-conjugated polymer blends

Phase separations in conjugated polymer (MEH-PPV) and non-conjugated polymer (PMMA) blended films are studied by photoluminescent (PL) near-field scanning optical microscope and spectrometer. The morphologies of blended films changed from stripe patterns to isolated islands as PMMA concentrations increased. The PL spectra in isolated micron dots are the same as MEH-PPV. Nevertheless, we found new PL spectra, peaked at 500 nm wavelength, in the PMMA matrix. Since, PMMA does not emit light, the new spectra indicate some MEH-PPV diluted in the PMMA rich regions. The excitons of MEH-PPV in the PMMA matrix are localized and emit light as PPV oligomers.