有機光電材料之合成及性質探討與應用

Syntheses, Properties and Applications of Organic Optoelectronic Materials

方福全(Fu-Chuan Fang)

指導教授 ： 汪根欉

國立臺灣大學/理學院/化學研究所/博士(2007年)

https://doi.org/10.6342/NTU.2007.01291

摘要

中文摘要

第一章:我們成功地合成並研究三種不同系列以4,5-diaza-9-9’-spirobifluorene (SB)為主的材料。第一種是利用分子掺雜的觀念,在三聚芴的材料中引入具有高電子親和力的(SB)官能基團，而不會影響寡聚芴分子主鏈的放光行為，因此以TSBT所製備出的元件相較於使用T3的元件具有較低的操作電壓與較高的放光效率。再者，由於在分子主鏈上引入噻吩基團，增加了分子共軛長度，所以TTSBTT的頻譜行為相對於TSBT有紅移的現象。第二種材料是藉由(SB)之高電子親和力，我們將双聚芴(SBT, SBB, SB2)同時做為電子傳導層以及主體材料以簡化磷光元件的製備,結果發現利用SBT所製成的紅光磷光元件之外部量子效率(~10.3%)，幾乎達到紅光掺雜物Btp2Ir(acac)的放光極限。第三種材料是利用SB建構donor-acceptor的系統，由於Cz2SB與TPA2SB的分子構形，在空間上donor與acceptor是互相垂直的關係，造成這兩個分子在基態沒有PET而在激態時有PET作用，而且研究結果顯示PET的效率可以藉由改變分子的不同電子特性來調控。

第二章:我們順利地合成並且探討以SB為配位基的離子性銥錯合物[Ir(ppy)2(SB)]+(PF6─)(橘紅光)與[Ir(dFppy)2(SB)]+(PF6─)(綠光)作為LECs的發光材料。由於SB配位基團提供了不錯的空間阻隔性質，使得利用[Ir(ppy)2(SB)]+(PF6─)以及[Ir(dFppy)2(SB)]+(PF6─)所製備而成的單層薄膜元件具有很不錯的發光效率。再者，我們也更進一步的引入主客體(Host/Guest)的觀念，將具較低階的[Ir(ppy)2(SB)]+(PF6─)(Guest)摻雜在具較高能接的[Ir(dFppy)2(SB)]+(PF6─)(Host)中，利用這樣的概念，並且於適當摻雜濃度下，主客體系統所做出來的元件效率是單純主體或客體元件的1.5倍。

第三章:我們成功地設計且合成出具有高三重態能階的主體材料(T1Si, SP3Cz2, TPA1Si, TPA2Si, CzSi以及TRZSi)並應用於磷光元件上，藉由材料性質分析可以發現，以上這幾個材料的三重態能階(triplet energy)都大於2.61 eV，這樣的能階大小足夠用來當作綠光及藍光磷光元件中的主體材料。以上這些高能階主體材料在熱性質上也有很好的表現(Td > 370 °C, Tg > 105 °C)。研究發現，利用以上幾個高能階材料所製成的元件確實具有很高的元件效率。

第四章:我們發展出一個利用鈴木偶合反應即可簡單且順利地引入分子自組裝單元到共軛分子上的合成方法，並且設計合成出一個一邊具有分子自組裝單元另一邊有硼酯官能基的重要中間體(4-pinacolatoboronic ester-benzenebiuret)。在共聚焦螢光光譜儀的研究下，我們發現在不同摻雜濃度下，兩種材料(OPV-Ph-biuret與T2-Ph-biuret)會自組裝成不同的薄膜型態，接著在掃描式電子顯微鏡的影像中，也發現單純的T2-Ph-biuret會形成球狀的微結構，而OPV-Ph-biuret則是會形成纖維狀的微結構，當兩個材料摻雜在一起時，則發現會有不一樣的型態出現，我們也發現於不同載體的條件下，由於不同載體之表面特性不同，所以兩個材料摻雜之後所形成的微結構也會隨之而改變。

關鍵字

三聚芴發光材料 ； 高三重態能階的主體材料 ； 分子自組裝

並列摘要

Abstract

Chapter 1 : Three series of novel 4,5-diaza-9-9’-spirobifluorene (SB)-incorporated organic materials have been synthesized and characterized. For the SB-incorporated terfluorene materials, we used the molecular doping strategy to introduce 4,5-diaza-9-9’-spirobifluorene (SB) as a functional substituent spirally linked to the conjugated oligofluorene backbone. TSBT exhibits lower device turn-on voltage and higher EQE than that of using T3. Because the conjugated backbone implant with thiophene rings increase the π-conjugation, the spectra of TTSBTT show substantial red shift compared to that of TSBT. Due to the high electron affinity of 4,5-diaza-9,9’-spirobifluorene moiety, SBT, SBB and SB2 were used as the ETL and host materials to simplify the electroluminescence devices. The high EQE (~10.3%) of SBT-simplified device is close to the limit of the emission quantum yield of Btp2Ir(acac) dopant. For the spiro-bridged D-A compound Cz2SB and TPA2SB, the perpendicular arrangement of the donor and acceptor limits the degree of the donor-acceptor interaction in the ground state and allows efficient PET to occur in the excited state. The experimental results show that the efficiency of this PET process was modulated by altering the electronic characteristic of the donor groups.

Chapter 2 : We have reported the syntheses and characterization of two novel cationic iridium complexes, [Ir(ppy)2(SB)]+(PF6─) (orange-red emission) and [Ir(dFppy)2(SB)]+(PF6─) (green emission), for solid-state light-emitting electrochemical cells. The devices using single-layered neat films of [Ir(ppy)2(SB)]+(PF6─) and [Ir(dFppy)2(SB)]+(PF6─) achieve high peak external quantum efficiencies and power efficiencies of (7.1%, 22.6 lm/W) and (7.1%, 26.2 lm/W), respectively. The high efficiencies indicate that the cationic transition metal complexes containing ligands with good steric hindrance (SB) are excellent candidates for highly efficient LECs. Moreover, when we use [Ir(dFppy)2(SB)]+(PF6─) as the host and [Ir(ppy)2(SB)]+(PF6─) as the guest, the host-guest LECs show much enhanced quantum efficiencies (power efficiencies) of up to 10.4% (36.8 lm/W), representing a 1.5X enhancement compared to those of pure host and guest devices.
Chapter 3 : The host materials with high energy gap (T1Si, SP3Cz2, TPA1Si, TPA2Si, CzSi and TRZSi) were synthesized and demonstrated with remarkable properties in the electrophosphorescence. The triplet energies of these host materials were above 2.61 eV in the neat film. In other words, these host materials possessing large triplet energies are suitable for green and blue phosphorescent OLEDs. Moreover, these host materials possess high decomposition temperature above 370 °C and also have high glass transition temperature above 105 °C. The multiple layer devices fabricated with these host materials show highly external quantum efficiency.

Chapter 4 : We developed a straightforward synthesis for introducing self-assembly units into the π-conjugated materials by Suzuki coupling reaction. The novel reagent, 4-pinacolatoboronic ester-benzenebiuret, is an unprecedented building block combining the biuret moiety for recognition function and boronic ester for Suzuki coupling. From the fluorescence confocal microscopy images, the unique morphologies were observed in the mixture of T2-Ph-biuret and OPV-Ph-biuret system with different concentrations. From the scanning electron microscopic (SEM) images, we discovered that T2-Ph-biuret formed globular nanostructure, OPV-Ph-biuret formed fiber nanostructure, and the mixture of 10% doping OPV-Ph-biuret within T2-Ph-biuret gave an irregular morphology on the glass substrates. We ascribed the specific morphology was formed by hydrogen-bonding and/or π-π interactions between OPV-Ph-biuret and T2-Ph-biuret on the substrate surface. Moreover, we observed some special nanostructures on different substrates (ITO and silicon wafer). The change in different shapes could be due to the fact that the surface energies of the substrates are different. In other words, the wetting behavior is different.

並列關鍵字

4,5-diaza-9-9’-spirobifluorene ； light-emitting electrochemical cells ； host materials with high energy gap ； self-assembly units

參考文獻

(12) T.-C. Chao, Y.-T. Lin, C.-Y. Yang, T.-S. Hung, H.-C. Chou, C.-C. Wu, K.-T. Wong, Adv. Mater. 2005, 17, 992.

(35) (a) K.-T. Wong, Y.-L. Liao, Y.-T. Lin, H.-C. Su, C.-C. Wu, Org. Lett. 2005, 7, 5131. (b) T.-C. Chao, Y.-T. Lin, C.-Y. Yang, T.-S. Hung, H.-C. Chou, C.-C. Wu, K.-T. Wong, Adv. Mater. 2005, 17, 992.

(21) T.-C. Chao, Y.-T. Lin, C.-Y. Yang, T.-S. Hung, H.-C. Chou, C.-C. Wu, K.-T. Wong, Adv. Mater. 2005, 17, 992.

(7) M.-K. Leung, C.-C. Yang, J.-H. Lee, H.-H. Tsai, C.-H. Lin, C.-Y. Huang, Y.-O. Su, C.-F. Chiu, Org. Lett. 2007, 9, 235.

(5) T.-C. Chao, Y.-T. Lin, C.-Y. Yang, T.-S. Hung, H.-C. Chou, C.-C. Wu, K.-T. Wong, Adv. Mater. 2005, 17, 992.