| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 106 === Two new polyimines PPI-1 and PPI-2 have been synthesized by polycondensation plus Suzuki coupling reaction and applied as hole-buffering layer (HBL) to enhance emission efficiency of polymer light-emitting diodes (PLEDs). Both polymers are thermally stable (Td 〉 300 oC, Tg of PPI-2 〉100 oC) owing to rigid pyrene backbone. Moreover, both PPI-1 and PPI-2 contain imine (azomethine) groups in main chain, which can lower the HOMO levels to improve hole-buffering ability. Multilayer PLEDs (ITO/PEDOT:PSS/HBL/SY/LiF/Al) have been fabricated using spin-coated PPI-1 and PPI-2 as HBL. Optimal maximum luminance and maximum current efficiency of the PPI-1-based device were 19,324 cd/m2 and 7.9 cd/A), whereas those of PPI-2-based device were 22,401 cd/m2 and 8.0 cd/A, respectively. Both are superior to the performance of device without the HBL (10,818 cd/m2, 2.5 cd/A). On the other hand, PPI-2-based device is superior to PPI-1-based device in terms of color purity as expressed in stable CIE coordinates. The results indicate that hole-buffer is a significant factor for efficient PLEDs and both PPI-1 and PPI-2 are potential hole-buffering materials for enhancing device performance of electroluminescent devices.
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