Tabletop Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation of Light-Emitting Organic Thin Films

Structural optimization of light-emitting polymer, or organic semiconductor, thin films deposited by tabletop 2.9 mum resonant infrared matrix-assisted pulsed evaporation (RIR-MAPLE) is investigated. Surface morphology of poly[2-methoxy-5-(2´-ethylhexyloxy)-1,4-(1-cyanovinylene) phenylene] (MEH-CN-PPV) and poly[2-methoxy-5-(2´-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) films are analyzed using optical and atomic force microscopy. These films are deposited using different target-to-substrate distances, ambient base pressures, laser fluences, and substrate temperatures, and with different target compositions comprising tetrahydrofuran (THF), chlorobenzene, toluene, o -xylene, chloroform, phenol:THF, and phenol:water. The corresponding optical behavior and chemical structure of the deposited films is investigated with photoluminescence spectroscopy and Fourier transform infrared spectroscopy. The use of a novel RIR-MAPLE emulsion target recipe enables the successful incorporation of MEH-CN-PPV and MEH-PPV polymers into ice matrices, and an MEH-PPV thin film with near-featureless surface morphology and an unprecedented rms surface roughness of 0.292 nm is demonstrated.