New Method to Create Semiconducting Covalent Polymer Networks for Optoelectronic Devices

Dr. Liang Yao has invented a unique technique for preparing semiconducting covalent polymer networks (CPNs). The new method is designed to advance the application of the materials in optoelectronic devices.

Covalent polymer networks (CPNs) are robust and tunable and hence are of great technological interest. They are, however, rarely used as semiconductors in optoelectronic devices because of poor material processability.  Dr. Liang Yao of LIMNO has come up with a simple, rapid, and robust approach to prepare CPN thin films based on an in situ thermal azide–alkyne cycloaddition (TAAC) without the use of solvents  or catalysts. The research paper published in Advanced Functional Materials, demonstrates the technique with perylenediimide and triazine-based monomers, enabling smooth and homogenous CPN films through solution processing and heat treatment within 10 minutes. The site-specific TAAC realizes semiconducting CPNs that are free of impurities or by-products. The tunable optoelectronic properties are realized by altering the reaction temperature, which actually influences the intermolecular self-assembly.

The obtained CPN films display high solvent resistance as well as good n-type semiconducting behavior, making them suitable for a series of multilayer solution-processed organic photovoltaics, where the presence of CPN films is known to enhance the solar energy conversion efficiency to more than 8% (7% in control devices) when the CPN is used in a planar-mixed heterojunction device architecture.