Miao Li: Energy harvesting with printed and solution-processed electronics makes IoT more efficient

Emerging printing and coating techniques, with their low-cost and ease of fabrication, make solution-processed and printed electronics very attractive. It enables researchers to explore new ways of material processing to develop devices, circuits, and systems, which are difficult to achieve with traditional wafer-based manufacturing techniques. M.Sc. Miao Li demonstrated in her doctoral dissertation the applicability of solution-processed and printed, low-cost radio frequency (RF) energy harvesters with unconventional semiconductor materials, such as organic polymers and metal oxides.

Billions of devices for the IoT and other ubiquitous electronics have been integrated into every aspect of the modern world and play a significant role in people’s life. There is a growing demand for an autonomous energy solution to address the myriad of charging elements. This need has brought out various energy harvesting solutions into the center of attention in both academic and business fields.

“Due to ease of implementation and availability, energy harvesting from RF sources is a promising energy solution. As the simplest active electronic components, rectifying diodes are extremely important devices in a RF energy harvesting system,” Miao Li says.

With the steady development in printing and coating methods, it offers an exciting path to large-area, high-volume, flexible, and ultra-low-cost electronics.

“The aim is to make low-cost solution processed components for RF energy harvesting. This implies to use low-temperate process, simple structure to minimize the fabrication cost, a good air-stability to avoid encapsulation,” Miao Li tells.

She continues to state, that solution processed diodes based on a single active layer represent a very simple structure which is readily fabricated by printing or coating technologies to enable fast, cost effective and high production.

Due to unique bonding and carrier transport mechanism, solution-processed organic and metal oxide diodes have dramatically different properties compared to their Si-based counterparts; their circuits have unique characteristics, and their optimization can differ strongly from conventional inorganic equivalents. Indeed, the performance of solution-processed devices cannot compete with conventional electronics.

“However, the development of solution-processed electronic components leads to great opportunities for the realization of low-cost and ﬂexible thin-ﬁlm devices. These thin-film devices can be easily incorporated into simple circuits to form a RF harvester to provide necessary functionalities to various smart objects of IoT at low cost,” Miao Li adds.

Miao Li believes that low-cost solution-processed devices with excellent air-stability and flexibility make them perfect to fit to the IoT devices and applications in near future.

The doctoral dissertation of M.Sc. Miao Li in the field of organic electronics titled Printed and Coated, Thin-Film Organic and Metal Oxide Diodes and Rectifier Circuits for RF Energy Harvesting will be publicly examined in the Faculty of Information Technology and Communication Sciences at Tampere University at 12:00 on Friday 01.04.2022 in auditorium SA203 S2 of the Sähkötalo building, Korkeakoulunkatu 8, Tampere. The Opponent will be Professor Henning Sirringhaus from University of Cambridge. The Custos will be Professor Donald Lupo from Tampere University.

The event can be followed via remote connection (Zoom).

The dissertation is available online at: https://urn.fi/URN:ISBN:978-952-03-2344-8

Photo: Wenqian Hui