側鏈含多面體矽氧烷寡聚物之聚(1,4-仲苯基乙烯)合成及其在高分子電激發光二極體上之應用

Abstract

本研究的主要目的在於合成以poly(p-phenylene vinylene)為基礎的共軛高分子，在側鏈導入多面體矽氧烷寡聚物(POSS)後，利用Gilch聚合方法使其與2-methoxy-5-(2-ethylhexyloxy)xylene共聚合成POSS-PPV-co-MEHPPV，並探討其在高分子發光二極體上之應用。合成出之POSS-PPV-co-MEHPPV其具有更高的熱裂解溫度(Td)及玻璃轉移溫度(Tg)；由於龐大的POSS官能基引入減少了分子鏈間的堆疊效應，因此在螢光放光效率(quantum yield)方面， POSS-PPV較純的MEHPP高出許多(0.85 vs. 0.19)。這些結果顯示藉由側鏈導入POSS可以有效提升發光材料的熱性質及發光效能。另外，POSS-PPV-co-MEHPPV對溶劑的可溶性，使其具備有良好的成膜性。在THF溶劑中，POSS-PPV最大放光波長在551nm；形成薄膜後，其最大放光波長在585 nm左右，為一紅光材料。我們利用旋轉塗佈的方式，製作了結構為ITO/PEDOT/polymer/Ca(Al)的雙層發光二極體元件，經過測試，在9.5V的電壓驅動下，10 mol% 的PPV-POSS較純的MEHPPV元件最大亮度高出約四倍(1998 vs. 395 cd/m2)。

A new series of high brightness and luminance poly(p-phenylenevinylene)-based copolymers, POSS-PPV-co-MEHPPV, which contain side-chain-tethered polyhedral oligomeric silsesquioxane (POSS) pendent units and poly(2-methoxy-5-[2-ethylhexyloxy]-1,4-phenyl- enevinylene) (MEHPPV), were synthesized through the Gilch polymerization method. This particular molecular architecture of PPV-POSS increases the quantum yield (0.85 vs. 0.19) of MEHPPV significantly by reducing the degree of interchain aggregation. Both the thermal degradation and glass transition temperatures increased substantially as the amount of POSS in MEHPPV increased. These soluble light emitting polymers show good film forming property and emit red light near 585nm in thin film. Double-layer LED device with an ITO/PEDOT/polymer/Ca /Al configuration were fabricated by using those polymers. The maximum brightness and luminance efficiency of 10 mol% PPV-POSS was five times as large as that of a similar light emitting diode incorporating pure MEHPPV (1998 vs. 395 cd/m2).