在高基板溫度下製備8-羥基喹啉鋁薄膜及其物性探討

Characterization of facial and meridional Alq3 thin films fabricated from physical vapor transport at high substrate temperatures

洪尚佑(Shang-Yu Hung)

指導教授 ： 邱寬城

中原大學/理學院/物理研究所/碩士(2014年)

https://doi.org/10.6840/cycu201400426

摘要

本實驗利用物理汽相傳輸法 (Physical vapor transport, PVT) 並固定粉末端溫度為375℃的條件下，成長 tris(8-hydroxyquinoline)-aluminum (Alq3) 的薄膜。並藉由改變基板溫度 (285℃ ~ 346℃) ，討論 facial Alq3 (fac-Alq3) 與 meridional Alq3 (mer-Alq3) 幾何異構物的轉換條件以及其所製成之薄膜的特性。在熱處理過程中， Alq3 異構物的轉換溫度幾近於 375℃。而在 PVT 過程中若使用 fac-Alq3 為粉末源， Alq3 異構物轉換溫度為314 ± 2℃。當基板溫度低於 314℃時，粉末源端的 fac-Alq3 就會轉變成低溫相的 mer-Alq3 。並且形成一根根由α-相 Alq3 構成的微米柱狀結構，其同調長度約 46 nm 。光激螢光光譜 (Photoluminescence, PL) 呈現 Alq3 典型的綠光。然而，當基板溫度超過 314℃時，沉積於基板上的 fac-Alq3 就會保持原本粉末的異構物狀態，並且自行組成具柔軟性的次微米纖維結構。這些纖維結構主要是由 fac-Alq3 組成δ-相的結晶。經過計算，其同調長度約57 nm 。此外， PL 光譜中也明顯量測出在高基板溫度下所製成之 fac-Alq3 薄膜的藍光特性。最後利用 Raman 量測，比較由 fac-Alq3 與 mer-Alq3 所形成之薄膜的差異。

關鍵字

基板溫度 ； 8-羥基喹啉鋁 ； 異構物轉換 ； 物理汽相傳輸法

並列摘要

During a thermal annealing process, the isomeric transformation from meridional (mer) into facial (fac) tris(8-hydroxyquinoline)-aluminum (Alq3) based on the infrared absorption was observed to be nearly complete around 375℃. Then, in a physical vapor transport process with post-annealed fac-Alq3 as source powder (at source temperature of 375℃), the effects from various substrate temperatures (Tsub from 285 to 346℃) on the transformation from fac-Alq3 into mer-Alq3 isomers re-condensed on the substrate were studied again, and an isomeric transformation occurs at Tsub = 314 ± 2℃. For Tsub < 314℃, the re-condensed mer-Alq3 isomers tend to aggregate to form closed-packed micron-rods, which are composed of α-phase crystallites with an average coherent length L ~ 46 nm. The photoluminescence (PL) spectra for these as-fabricated mer-Alq3 films show typical green emission. However, for Tsub > 314℃, the adsorbed fac-Alq3 molecules on the substrate preserve their corresponding isomeric structure from the post-annealed fac-Alq3 source and self-organize into flexible submicron-fibers. These samples are dominated by δ-phase crystallites with L ~ 57 nm. The PL spectra for these as-fabricated fac-Alq3 films fabricated at higher Tsub do emit blue luminescence. Besides, Raman scattering for these mer-Alq3 and fac-Alq3 molecules are also compared.

並列關鍵字

physical vapor transport ； substrate temperature ； isomeric transformation ； Alq3 ； tris(8-hydroxyquinoline)-aluminum

參考文獻

[1] C.W. Tang, S.A. VanSlyke, Appl. Phys. Lett. 51 (1987) 913.

[2] W. Brütting, Physics of Organic Semiconductors, Wiley-VCH, Weinheim, 2005.

[3] Z.H. Kafafi, Organic Electroluminescence, Taylor & Francis, Boca Raton, 2005.

[5] T. Fukushima, H. Kaji, Org. Electron. 13 (2012) 2985.

[11] M. Muccini, M.A. Loi, K. Kenevey, R. Zamboni, N. Masciocchi, A. Sironi, Adv. Mater. 16 (2004) 861.