芘並咪唑和菲並咪唑在3,5號位不同取代衍生物之合成、性質探討與應用

Abstract

本研究著重於開發具有潛力之藍光有機發光材料，針對芘並咪唑（Pyrene[4,5-d]imidazole）與菲並咪唑（Phenanthrene[9,10-d]imidazole）為核心結構，於3,5號位引入1-位取代芘基、2-位取代芘基，以及和芘基同樣具有TTA-UC特性的蒽基。設計並合成六種新穎衍生物，包括Pyi35d1-Py、Pyi35d2-Py、Pyi35dAn、Phi35d1-Py、Phi35d2-Py及Phi35dAn。藉由結構修飾，探討這些分子之熱穩定性、光電性質與分子堆疊行為，並進一步探討其在有機發光二極體（OLED）元件中作為發光材料的表現。 於物性方面，熱重分析（TGA）與差示掃描量熱儀（DSC）結果顯示，所有化合物皆具有良好的熱穩定性。紫外-可見光吸收光譜與螢光光譜分析指出，這些化合物在溶液中可發出明亮藍光，具高量子產率。另透過循環伏安法（CV）探討其電化學行為，並結合密度泛函理論（DFT）計算，分析分子軌域分布與HOMO/LUMO能階之對應關係。單晶X-ray繞射分析進一步顯示，部分化合物因具扭曲構型，可有效抑制分子間的π – π堆疊，進而降低激子淬熄現象，有助於提升發光表現。 在應用層面，將本研究所合成之材料Pyi35d1-Py製程元件，並進一步探討其於不同摻混比例下，搭配客發光體DPaNIF時的元件發光表現。實驗結果顯示，Pyi35d1-Py在特定混摻比例可顯著提升元件的電流效率與亮度，展現良好的元件特性。由此可知，適當的分子設計與混摻條件調控，有助於提升元件效率，進一步實現藍光材料於OLED應用上的實用性。

This study focuses on the development of promising blue-emitting organic materials. Using pyrene[4,5-d]imidazole and phenanthrene[9,10-d]imidazole as core structures, derivatives were designed by introducing substituents at the 3,5-positions, including 1-substituted pyrene, 2-substituted pyrene, and anthracene—an emitter exhibiting triplet–triplet annihilation upconversion (TTA-UC) properties similar to pyrene. Six compounds were synthesized : Pyi35d1-Py, Pyi35d2-Py, Pyi35dAn, Phi35d1-Py, Phi35d2-Py, and Phi35dAn. Through structural modification, their thermal stability, photophysical and electrochemical properties, and molecular packing behavior were systematically investigated, along with their performance as emissive materials in organic light-emitting diodes (OLEDs). In terms of physical properties, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed that all compounds possess excellent thermal stability. UV–vis absorption and photoluminescence spectra indicated that these compounds emit intense blue fluorescence in solution with high quantum yields. Electrochemical properties were further explored using cyclic voltammetry (CV), and density functional theory (DFT) calculations were employed to analyze the molecular orbital distribution and HOMO/LUMO energy levels. Single crystal X-ray diffraction showed that certain compounds adopt twisted conformations, which effectively suppress π–π stacking and thus reduce exciton quenching, enhancing solid-state emission efficiency. For device applications, Pyi35d1-Py was employed for device fabrication. Further investigations were conducted on the device’s electroluminescent performance when blended with the guest emitter DPaNIF at different doping ratios. The experimental results showed that Pyi35d1-Py could significantly enhance the current efficiency and luminance of the devices at specific blending ratios, demonstrating favorable device characteristics. This indicates that appropriate molecular design and blending condition optimization can effectively improve device efficiency, thereby advancing the practical use of blue-emitting materials in OLED applications.