Photopolymerization studies of a light-emitting liquid crystal with methacrylate reactive groups for electroluminescence

Woon, Kai L.; Liedtke, Alicia; O'Neill, Mary; Aldred, Matthew P.; Kitney, Stuart P.; Vlachos, Panagiotis; Bruneau, Amaury; Kelly, Stephen M.

Abstract

Light-emitting reactive mesogens are promising materials for photolithographically processable organic light-emitting diodes (OLEDs). We study the photopolymerization of a fluorene-based mesogen with methacrylate photoreactive groups. We find that there is no significant change in the photoluminescence quantum efficiency when the mesogen is photopolymerized in a glovebox with oxygen and water concentration at < 20 parts per million. There is significant quenching of luminescence when the photopolymerization is carried out in a less controlled environment. A real-time measurement is used to monitor changes in the FTIR spectrum of the compound during polymerization. No photo-initiator is added to the mesogen suggesting that the photopolymerization is self-initiated by the chromophore. We show that the self-initiation does not proceed by fragmentation of the aromatic core and suggest an alternative mechanism.

Citation

Woon, K. L., Liedtke, A., O'Neill, M., Aldred, M. P., Kitney, S. P., Vlachos, P., Bruneau, A., & Kelly, S. M. Photopolymerization studies of a light-emitting liquid crystal with methacrylate reactive groups for electroluminescence. Paper presented at Liquid Crystals XII

• Presentation Conference Type: Conference Paper (unpublished)
• Conference Name: Liquid Crystals XII
• Acceptance Date: Dec 31, 2008
• Publication Date: Aug 28, 2008
• Journal: Proceedings of SPIE - The International Society for Optical Engineering
• Print ISSN: 0277-786X
• Publisher: Society of Photo-optical Instrumentation Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 7050
• Article Number: 70500E
• Pages: 0 - 0
• DOI: https://doi.org/10.1117/12.794248
• Keywords: Liquid crystals, reactive mesogens, photoluminescence, organic semiconductor, crosslinking, fourier transform infra-red spectroscopy, polymer network
• Public URL: https://hull-repository.worktribe.com/output/400297