摘要
近年來，高分子太陽能電池的研究開發受到極大的矚目，為能有效達到高的光電轉換效率，光吸收層材料的深入基礎研究是必須的，其中的一個重點是該薄膜層中共軛高分子的結構及共軛高分子與受體（一般為C60或C¬70為主體之材料）摻混之相容性與相分離形態學的操控。本論文針對目前最廣泛被使用之材料 poly(3-hexylthiophene) (P3HT)與PCBM所形成的摻合體相容性、結晶行為與形態學等進行系統性研究。我們將製備摻合體所使用的2 wt%溶液在室溫下靜置不同時間後再進行鑄膜，我們發現當靜置時間超過12小時，溶液會產生凝膠化現象，從SAXS、AFM等證實P3HT在凝膠化過程中形成奈米鬚結構。之後我們將靜置不同時間的溶液（或凝膠）鑄膜，探討所形成的P3HT/PCBM薄膜中兩成分的相容性及P3HT之結晶動力學等，以瞭解溶液處理條件是否會影響薄膜的形態學及結晶行為等。實驗結果發現，不管溶液是否有經過靜置，P3HT在P3HT/PCBM摻合薄膜的結晶速率皆隨著PCBM含量增加而下降，此顯示P3HT與PCBM在分子層級具有相當顯著的相容性。有趣的是，當溶液靜置時間超過一星期，在凝膠態所鑄造的薄膜中，P3HT的結晶速率比用新鮮溶液製備的膜中的結晶速率要慢許多。我們認為在凝膠態所鑄造的薄膜中，幾乎所有的P3HT都形成奈米鬚，而該奈米鬚在P3HT晶體熔點以上，仍可維持一定的穩定性，所以在降溫過程中，P3HT必須在奈米鬚所提供空間中結晶，由於該空間的尺度拘限性，加上所需的晶核密度大幅增加，所以導致結晶速率大幅下降。我們另外在SAXS圖譜中發現P3HT會呈現一個特徵尺度約4.5 nm的奈米結構，該奈米結構在80 ~ 90 oC會熔化，但降溫會再出現，顯示為一熱可逆之平衡或亞穩結構。

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