Synthesis of poly(N-9-ethylcarbazole-exo-norbornene-5,6-dicarboximide) for hole-transporting layer in hybrid organic light-emitting devices

• Published in: Journal of polymer science. Part A, Polymer chemistry Polymer chemistry, 2010-11, Vol.48 (22), p.5189-5197
• Main Authors: Choi, Myeon-Cheon, Hwang, Jae-Chul, Kim, Chiwan, Kim, Youngkyoo, Ha, Chang-Sik
• Format: Article
• Language: English
• Subjects: Applied sciences; carbazole; Composites; Devices; Electronics; Exact sciences and technology; Forms of application and semi-finished materials; hole-transporting materials; hybrid OLED; Indium tin oxide; Luminance; Molecular orbitals; Nanocomposites; Nanomaterials; Nanostructure; Optoelectronic devices; organic light-emitting device; Organic polymers; Physicochemistry of polymers; Polymer industry, paints, wood; Polymers with particular properties; polynorbornene; Preparation, kinetics, thermodynamics, mechanism and catalysts; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon dioxide; Technology of polymers
• ISSN: 0887-624X; 1099-0518; 1099-0518
• DOI: 10.1002/pola.24318

We synthesized new polynorbornene dicarboximide (PCaNI) functionalized with hole-transporting carbazole moieties and its copolymer (PCaNA) by ring-opening metathesis polymerization (ROMP), where the PCaNA was further reacted with 3-amino-triethoxysilane to prepare PCaNI/silica hybrid. We also investigated the feasibility of PCaNI and PCaNI/silica hybrid (PCaSi) as a hole-transporting material for hybrid organic light emitting devices (HOLEDs). To improve the performance of the PCaNI-based HOLEDs, N,N′-diphenyl-N,N′-(3-methylphenyl)-[1,1′-biphenyl]-4-4′-diamine (TPD) was also introduced into the PCaNI matrix. Results showed that PCaNI exhibited high glass transition temperature (~260 °C) and high optical transparency in the visible region. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of PCaNI were measured as 5.6 and 2.2 eV, while the TPD-doped PCaNI showed 5.7 eV (HOMO) and 2.6 eV (LUMO). The PCaNI/silica hybrid nanolayers showed excellent solvent resistance due to the formation of covalent bonds between ITO and PCaNI. The HOLEDs with PCaNI/TPD or PCaSi/TPD hybrid nanolayers exhibited relatively higher luminance (~10,000 cd/m²), lower operating voltage (~6.5 V at 300 cd/m²), and higher current efficiency (~2.7 cd/A).