Lasers and light-emitting diodes made with semiconducting conjugated polymers and rare earth complexes

Semiconducting (conjugated) polymers have several properties that are advantageous for photonic applications; they have high fluorescence efficiencies (>60%), emit at wavelengths that span the entire visible spectrum, are mechanically flexible, and can be deposited as uniform thin films by casting from solution. Since the invention of the polymer light-emitting diode (LED), rapid progress has been made and it is now expected that displays made from arrays of polymer LEDs will soon be commercially available.; The first topic of this dissertation is the use of conjugated polymers as the gain material in solid state lasers. By measuring the gain and loss in thin-film planar waveguides, it was shown that narrow-line emission was a result of amplified spontaneous emission (ASE). Resonant structures were developed to make polymer lasers. Distributed feedback lasers were found to have low thresholds (100 W/cm2) because they have a long gain region and highly reflective gratings. It has not been possible so far to make a polymer diode laser because of charge induced absorption and metal electrode absorption. Potential solutions to these problems have been devised.; Conjugated polymers typically have a broad emission spectrum (100–200 nm full width at half maximum). This is undesirable for several applications that require monochromatic emission. To address this problem, blends of rare earth complexes in polymer films were made. The complexes were designed such that energy is transferred from the polymer to the rare earth ion, which yields monochromatic emission. The photoluminescence and electroluminescence of these blends was studied. LEDs made with Eu complexes have pure red emission and a spectral linewidth of 3.5 nm (FWHM); they are very promising for applications in full color displays and photonic crystals.