Research team led by Prof. ZHU Pengli from the Shenzhen Institute of Advanced Technology (SIAT) of Chinese Academy of Sciences and Prof. CHI Zhenguo from the Sun Yat-sen University, have provided a new strategy to enhance the long-term stability of ultralong organic phosphorescence (UOP) materials based on epoxy resin in high-temperature-humidity conditions via hydrophobic effect. 

The study was published in Aggregate on Oct. 10. 

UOP materials have long lifetime with unique optical phenomenon, which can be applied in a wide range field, such as displays, sensing, information encryption, bioimaging and so on. Among these, polymeric UOPs are attracted more attention due to good film-forming stability, cost-effectiveness, and suitability for large-area production. However, achieving good water/moisture-resistance for long-term environmental stability is a challenge, which limits the service conditions of UOP materials. 

Epoxy resin (EP) is a kind of covalent cross-linked polymeric material which features excellent physical, mechanical, and insulation properties. The composite materials based on EP have been widely used in architecture, machinery, electronic packaging, etc. Moreover, the cross-linked network of epoxy is easily modulated by formulations, which also has been applied in as multifunctional polymers. 

In this study, with the introduction of different alkyl-chain length to the hardeners and emitters, a series of polymeric UOPs based on the EP curing system were obtained and exhibited significant hydrophobic effect. Remarkably, no obvious decreased in UOP emission were observed after 85℃/85% relative humidity reliability test for 7 days.  

The results revealed that rigid covalent crosslinking networks suppressed the quenching of triplet excitons while the hydrophobic microenvironment afforded good water/moisture-resistance ability for the polymeric UOPs. 

"The polymers have been successfully applied in various fields, including films coating (on different substrates), prepreg for glass fibers and thread, and optical packaging, due to its outstanding environmental stability, processability, and adhesive properties," said Prof. ZHU. 

The design strategy of the polymeric UOPs. (Image by SIAT)

Media Contact:
ZHANG Xiaomin
Email:xm.zhang@siat.ac.cn