KEY POINTSOsaka University-led team develops colorless transparent organic solar cell that generates power from near-infrared lightOrganic semiconductor design transmits visible light while selectively absorbing near-infrared wavelengths for power conversionTechnology could be integrated into windows, vehicles and wearables without reducing daylight or changing appearance
Researchers developed a transparent organic solar cell that generates power from near-infrared light. Note: Japanese text in the original image from press release has been translated into English by our editorial team.
artience Corp.
A research group led by Osaka University has developed a colorless, transparent organic solar cell that can generate electricity from near-infrared light, opening a potential path to power-generating windows for buildings and vehicles without affecting visibility or design, according to an Aug. 4 release.
The joint team included researchers from Osaka University’s Institute of Scientific and Industrial Research and Graduate School of Engineering, the University of Tokyo’s Institute for Solid State Physics, Aoyama Gakuin University’s School of Science and Engineering, and artience Corp.
Organic solar cells use organic semiconductor materials in their power-generating layer and have drawn attention as a next-generation energy technology because they can be lightweight and flexible. Conventional organic solar cells, however, generally generate power by absorbing visible light, which makes them appear colored and has limited applications in places where transparency and appearance matter.
The group developed an organic semiconductor material that absorbs near-infrared light selectively while barely absorbing visible light. Using that material, the researchers confirmed that an organic solar cell could generate power while maintaining high transparency.
The release said the team established both a design approach for organic semiconductors that transmit visible light while absorbing only near-infrared light and a method for converting near-infrared energy into electricity. Near-infrared light corresponds to wavelengths from about 780 nanometers to several micrometers and accounts for roughly 30% to 40% of the energy in sunlight. Visible light corresponds to wavelengths of roughly 400 to 780 nanometers.
The newly developed thin film absorbs near-infrared light efficiently while showing high visible-light transmittance, making it appear nearly colorless and transparent to the human eye. A solar cell incorporating the molecule into its power-generation layer operated while maintaining high visible transparency and achieved an external quantum efficiency of more than 20% in the near-infrared region.
The researchers also detected pulse signals using near-infrared light with the colorless transparent organic photoelectric conversion device developed in the study, indicating possible applications in wearable devices. Wearables are small devices worn on the body to measure health and biometric data such as heart rate and pulse.
The group said the result could support development of transparent power-generating devices that can be integrated into building and automobile windows as well as wearables. In Japan, building-integrated photovoltaics refer to solar power devices incorporated into parts of a building such as roofs, walls or windows.
The study was published in the Journal of the American Chemical Society on Aug. 4, 2024, under the title “Laporte-Rule-Guided Molecular Symmetry Control of NIR-Selective Organic Semiconductors for Colorless and Transparent Photovoltaics.”
The paper’s authors are Soichi Yokoyama, Kenta Kuroishi, Shunsuke Tanaka, Yuta Murotani, Ryusuke Matsunaga, Shuhei Kawaoka, Reo Ohno, Miki Hasegawa, Akinori Saeki, Jun Yoshinobu and Yutaka Ie. The research was supported by Japanese government grants including KAKENHI, JST programs and the Cabinet Office’s BRIDGE program.
AloJapan.com