A method to recycle used electronic devices into other electronic devices has been developed, which is expected to provide a new direction for solving environmental problems and creating a sustainable future electronic device industry.

UNIST (President Yong-Hoon Lee) Chemistry Department Professor Kyo-Seung Shim's team has developed flexible electronic devices and wearable devices based on organic materials that can recover and recycle all materials. The developed electronic devices have increased their efficiency by introducing eco-friendly and economical processes from production to recycling.

Recently, active research and technological development on wearable electronic devices utilizing organic electronic materials are in progress.

Accordingly, various types of organic electronic waste are increasing. Recycling technology to date has focused only on inorganic materials such as glass used in LCD substrates and metal used as electrodes.

Professor Shim Kyo-seung added, “We utilized an eco-friendly and economical process using solvents that are harmless to the human body,” and “We selected only recyclable, organic-based electronic materials rather than inorganic ones to create flexible wearable electronic devices.”

The research team used drop casting to minimize material waste and produce various passive and active components. Drop casting is a method of forming a film by dropping a solution onto a substrate and then heat treating it.

The recyclability of the manufactured organic electronic materials, such as organic conductors, insulating gels, and semiconductors, was evaluated. In the case of organic conductors, it was confirmed that they could be recycled more than 5 times, organic insulating gels could be reused more than 30 times, and organic semiconductors could be recycled about once.

Based on the developed recyclable flexible electronic devices, the research team demonstrated 'closed-loop recycling' between electronic devices. Closed-loop recycling is a method in which the materials of manufactured electronic devices are recycled and reconstituted into other electronic devices when their lifespan ends. The research team perfectly extracted the original device characteristics without material loss by using a recycling method based on selective dissolution of materials.

Professor Shim Kyo-seung said, “This study is the first to suggest solutions to environmental problems that arise during the development of the electronics industry using organic electronic materials that have been overlooked so far,” and “We expect that the results of this study will be a leading result and core technology that suggests a new direction for a sustainable future electronics industry.”

This study, in which Park Hae-chan, a graduate student in the combined master's and doctoral program at UNIST, participated as the first author, was published online on December 6 in Nature Electronics, one of the world's most prestigious international academic journals. The research was conducted with the support of the National Research Foundation of Korea (NRF) under the Ministry of Science and ICT and Ulsan National Institute of Science and Technology (ULST).