利用介電層表面處理提升負型有機薄膜電晶體在大氣下之穩定性

Abstract

本研究選用不同高分子介電材料，將其塗佈於二氧化矽的絕緣層表面，研究不同高分子修飾層對負型有機電晶體元件特性之影響，特別針對元件於一般大氣下之穩定性做深入的探討。由實驗結果發現選擇適當的高分子修飾層能夠有效的提高元件效能並且表現出較好的穩定性。我們知道在一般的二氧化矽表面上會有很多SiOH鍵結，這些鍵結往往對於負型有機電晶體有抑制其元件電性的效果，容易於介電層表面產生SiO-等官能基而局限電子。疏水性強的高分子材料能夠有效的減少在二氧化矽表面上的電子陷阱(SiO-)，並且可以由原子力顯微鏡與X光晶格繞射圖譜等分析結果發現這些高疏水性的表面能夠使有機半導體分子有更好的晶格排列性，進而提高負型電晶體之元件特性與穩定性。

Improved air-stability of n-channel organic thin film transistors using N,N’-dioctyl-3,4,9,10-perylene tetracarboxylic diimide as the active material has been demonstrated by modifying the dielectric surfaces with various polymer insulators. The appropriate polymer dielectric plays an important role in the n-channel conduction for organic transistors. The hydrophobic nature of the polymer surfaces inhibits the protonation reaction of siloxyl groups on the SiO2 surface, leading to less SiO- groups, which could behave as electron trapping sites. Additionally, the hydrophobic polymer surface can also enhance the crystallinity of PTCDI-C8 thereby improving the transfer characteristics. Among the polymer insulators, the device modified with hydroxyl-free polymers exhibited better air-stability. Overall, the improved stability is attributed to the passivation of the electron trapping sites on the dielectric surfaces.