The Japan Institute of Advanced Industrial Technology (referred to as the Industrial Research Institute) and others have found that after the "caffeic acid" contained in coffee is added to organic semiconductor components, the current flowing can be increased by up to 100 times. Organic semiconductors are used in OLED screens used in displays and organic thin-film solar cells. If plant materials can be fully utilized, it will contribute to the development of products with low environmental impact.
Caffeic acid, also known as 3,4-dihydroxycinnamic acid, exists in plants such as coffee beans. A research team composed of the Institute of Industrial Research and the University of Tsukuba made predictions based on the chemical structure characteristics of caffeic acid, which contributes to the improvement of the performance of organic semiconductors.
The research team has trial-produced an organic semiconductor device using caffeic acid with a size of a few millimeters square and a thickness of 350 nanometers. A thin film of caffeic acid was formed between an organic semiconductor developed for solar cells and an electrode.
Measurements of the ease with which the current flowed showed that the current increased up to 100 times compared to when caffeic acid was not added.
Ordinary devices generally use metal oxides and conductive polymer materials between organic semiconductors and electrodes. It is said that if caffeic acid can be used, in addition to eliminating the need to use precious metals, the environmental load will also be reduced.
"Caffeic acid, which can be obtained from plants, can improve the electrode performance of organic semiconductors as well as conventional materials. This discovery is a step towards the development of devices based on biomaterials," said Yukio Akaike, chief researcher at the Industrial Research Institute.
Products using organic semiconductors include OLED screens and organic thin-film solar cells. The demand for OLED screens such as smartphones and TVs is increasing. Organic thin-film solar cells can also be bent and installed in a wide range of places, so growth is expected in the future. The research team will purportedly aim to develop all-biomass devices in which organic semiconductors and electrodes also use biological resources.
