Emulsion Target Process-Structure-Property Relationships in Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation (RIR-MAPLE) for Selective Deposition of Crystalline Phases in Polymer Thin Films*

The semi-crystalline phase of polyfluorene (β-PFO) is desirable for blue polymer LEDs because it yields higher carrier mobilities that lower operating voltage and increase device lifetime. However, the use of poor solvents in solution-based deposition to obtain high β-PFO content also degrades surface quality. Previous research on emulsion-based RIR-MAPLE deposition has shown that emulsion characteristics impact β-PFO content in thin films. In contrast to solution-based deposition, RIR-MAPLE increases β-PFO content to 6% without degrading surface morphology.
The goal of the current work is to establish the process-structure-property relationships of RIR-MAPLE emulsion targets to achieve 42% β-PFO content (for phase stability) by controlling emulsion chemistry and deposition rate. The emulsified polymer particle size will be measured by dynamic light scattering, the structure of PFO films will be characterized by atomic force microscopy, and the β-PFO concentration will be measured using photoluminescence and/or UV- absorbance spectroscopy. In addition, basic device performance of PFO-based LEDs will be measured to determine the impact on device performance.