| Summary: | 碩士 === 國立中正大學 === 化學工程研究所 === 102 === In the last two decades, much research had been dedicated to improving the performance of polymer light emitting diodes (PLEDs), and among them, blending conjugated polymer with a certain ratio of inert polymer has served as a useful processing parameter. This study utilized light scattering, photoluminescence (PL), and images from scanning electron microscopy (SEM) to investigate the aggregation properties of Poly-[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV)/PMMA/toluene system in solution and thin-film state. We have conducted a series of experiments on varying the blending ratio of PMMA (20%~80%) at fixed total polymer concentration, or varying the PMMA concentration and chain length (120 and 996 kDa) at fixed MEH-PPV concentration (1.5 and 3.5 mg/mL), revealing that the PL spectra of solution-cast thin films are sensitively dependent on the initial concentration of MEH-PPV solution as well as on the PMMA molecule weight. We found that low-concentration MEH-PPV solutions along with blending short-chain PMMA lead to improved (blue-shifted) PL spectra. Though the underlying physics needs to be further explored, the present findings provide more specific information for improving the device performance based on hybrid polymer solutions.
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