트리페닐렌 및 터페닐을 기반으로 한 새로운 유기 발광 다이오드용 정공수송물질에 관한 연구

Alternative Title
Novel Hole Transport Materials Based on Triphenylenes or Terphenyls for Organic Light Emitting Diodes
Author(s)
박종억
Advisor
高光潤
Department
일반대학원 화학과
Publisher
The Graduate School, Ajou University
Publication Year
2011-02
Language
kor
Keyword
발광 다이오드트리페닐렌터페닐LED정공수송물질
Abstract
중심구조가 triphenylene 유도체인 DPL(diphenyltriphenylene) 또는 terphenyl 유도체인 TP(diphenylterphenyl)이고, diarylamine 치환체가 2개에서 4개 도입된 구조의 새로운 유기 발광 다이오드용 정공 전달 물질을 합성하여 물리적, 광학적, 전기화학적 특성을 살펴보았고 이들 물질들을 이용하여 소자를 제작하고 평가하였다. 이들 물질들은 적당한 승화성을 갖고 있으므로 승화 정제가 가능하였고 가시광선 영역에서 흡수가 일어나지 않으므로 빛의 간섭에 의한 색좌표의 이동이나 발광 효율 감소 현상이 나타나지 않았다. 유리전이온도가 125 ℃ ~ 229 ℃이고, 분해점이 426 ℃이상으로 이보다 낮은 온도에서는 열분해가 일어나지 않으므로 높은 열적 안정성을 갖고 있음을 알 수 있었다. 이것은 중심구조인 여러 개의 페닐기로 치환된 triphenylene과 terphenyl 유도체가 단단하고 크기가 크기 때문이다. 재료의 HOMO 값은 5.17 eV ~5.47 eV로 정공주입층 또는 정공수송층으로 사용할 수 있는 정공 전달 재료로 적절한HOMO 값을 나타내었고 cyclic voltammetry에서 반복 산화 전압을 가하였을 때 산화에대한 안정성이 우수하였다. 이들 물질을 정공수송층으로 사용하여 제작한 유기 발광 소자에서, 중심 구조가terphenyl 보다는 triphenylene이 더 우수한 특성을 보여주었고, 그중에서 triphenyl-triphenylene 또는 tetraphenyltriphenylene 보다는 diphenyltriphenylene이 더 좋은특성을 나타내었으며, 특히 아민 치환기가 triphenylene에 직접 치환되어 있는 7DPL과 6DPL 이 가장 우수한 특성을 나타내었다. 아민 치환기가 N-phenyl-1-naphthyl-amine으로 동일한 경우에 7DPL 중 하나인 HT02 가 가장 우수한 특성을 나타내었다.발광층 재료를 tris(8-hydroxyquinoline)aluminium으로 사용한 녹색 소자에서 이들물질을 정공수송층으로 사용하여 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB)과 비교하였을 때, turn-on voltage는 7DPL 과 6DPL 에서 대부분 3.0 V로 0.5 V낮았고, driving voltage는 HT09 가 4.2 V로 1.4 V나 낮았으며, maximum luminance는HT13 이 62290 ㏅/m²로 390%나 높았고, maximum current efficiency는 HT13 이 8.95㏅/A로 100%나 높았고, maximum power efficiency는 HT06 과 HT13 이 3.89 lm/W로 40% 향상 되었다. 따라서 HT13 이 정공수송층 재료로 가장 좋은 특성을 나타내었고 모든평가 항목에서 NPB에 비교하여 매우 우수한 특성을 보여주었다.
Alternative Abstract
Triphenylene derivatives DPLs (diphenyltriphenylenes) and terphenyl derivatives TPNs (diphenylterphenyls) were synthesized as novel hole transport materials for organic light emitting diodes (OLEDs). Physical, optical and electrochemical properties of these materials were examined and OLED devices using these materials as the hole transport layer were fabricated and evaluated. These materials could be refined by sublimation method and did not absorb visible light. Therefore, changes in the color coordination by light interference and decrease in emission efficiency did not occur. The glass transition temperature of these materials was observed in the range of 125 ℃ ~ 229 ℃ and they did not show any decomposition until 426 ℃, meaning that they are thermally stable. The excellent thermal stability of the materials may be attributed to rigid and bulky polyphenyltriphenylene and polyphenylterphenyl units in the molecular core structure. The HOMO energy levels of the materials were in the range of 5.17 eV ~5.47 eV, showing that the materials can be used as appropriate hole injection or hole transport material for OLEDs. Cyclic voltammetry showed that redox processes are reversible. The device performances of OLEDs prepared using the materials as the hole transport layer were investigated. The materials containing a triphenylene as a central unit showed more excellent characteristics than a terphenyl analog. In the triphenylene materials, the materials containing a diphenyltriphenylene showed better characteristics than a triphenyltriphenylene or tetraphenyltriphenylene. 7DPL and 6DPL, having amino groups substituted directly at triphenylene showed the most outstanding characteristics. In materials containing N-phenyl naphthylamine, especially HT02, one of the 7DPL derivatives, had the most excellent characteristics. These materials were used as a hole transport layer for green devices with tris(8-hydroxyquinoline)aluminium as an emitting material. The device performance based on the materials was compared with that of a 4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) based device. The turn-on voltages in the 7DPL and 6DPL were almost 3.0 V, which was lower by 0.5 V than in the case of NPB. The driving voltage of HT09 was 4.2 V, which was lower by 1.4 V. The maximum luminance of HT13 was 62290 ㏅/m², which was 4.9 times higher. The maximum current efficiency of HT13 was 8.95 ㏅/A, which was 2.0 times higher. The maximum power efficiencies of HT06 and HT13 were 3.89 lm/W, which was 1.4 times higher. In conclusion, we have found that HT13 showed the most excellent characteristics as a hole transport material, better than those of NPB.
URI
https://dspace.ajou.ac.kr/handle/2018.oak/17881
Fulltext

Appears in Collections:
Graduate School of Ajou University > Department of Chemistry > 3. Theses(Master)
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse