共軛高分子/PMMA混摻系統之光散射及光譜性質研究

Investigations of Light Scattering and Spectroscopic Properties in Conjugated Polymer/PMMA Blend Systems

蘇建又(Chien-Yu Su)

指導教授 ： 華繼中

國立中正大學/工學院/化學工程學系/碩士(2014年)

摘要

近二十年來，已有許多學者們致力於研究高分子有機發光二極體 (PLED) 之效能改善，部分研究指出適量地摻混非導電高分子 (如聚苯乙烯等) 進入其主動層能增加其發光效率並改善其加工性質，因此研究混摻共軛高分子之溶液性質與成膜後性質的關聯性為一重要課題。本研究使用一系列光散射、光致螢光光譜實驗，輔以場發射掃描電子顯微鏡 (SEM) 之圖像，探討不同分子量之PMMA與混摻比例於不同濃度之Poly-[2-methoxy-5-(2′-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV) 甲苯溶液 (1.5及3.5 mg/mL) 中，對MEH-PPV聚集體性質所造成的影響，及其對於薄膜發光性質之間的關聯性。於固定MEH-PPV溶液濃度，並摻混不同濃度之PMMA溶液的實驗中發現，改變初始MEH-PPV濃度及摻混不同分子量之PMMA對於改善其薄膜發光性質有一定的選擇性，分別於低MEH-PPV初始濃度及摻混較低分子量之PMMA情況下得到較佳的結果。此外，在SEM之圖像中也觀察到MEH-PPV聚集體結構有被破壞的情形。綜合以上結果初步推論為低分子量之PMMA在MEH-PPV溶液中有滲入MEH-PPV聚集體的現象。以上發現，希望未來能於此類系統的應用方面，提供一些參數調整的方向與具體依據，進而改善所製備元件之光電效能。

關鍵字

光致螢光光譜 ； 光散射 ； 混摻高分子溶液 ； 共軛高分子 ； 聚集體性質

並列摘要

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.

並列關鍵字

photoluminescence ； light scattering ； hybrid polymer solution ； conjugated polymer ； aggregation properties

參考文獻

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Chen, S. H., Su, A. C., Chang, C. S., Chen, H. L., Ho, D. L., Tsao, C. S., Peng, K. Y., and Chen, S. A., ‘‘Aging of Poly(2-methoxy-5-(2‘-ethylhexyloxy)-1,4-phenylenevinylene)/Toluene Solutions and Subsequent Effects on Luminescence Behavior of Cast Films,’’ Langmuir 20, 8909-8915 (2004).

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