Nanotechnologies / Materials
Alternative energies, Agrivoltaics, Smart devices

Development of non-fused acceptor materials toward
organic solar cells
Department of Soft Nanomaterials, SANKEN (The Institute of Scientific and Industrial Research)
Assistant Professor Seihou Jinnai

https://researchmap.jp/jinnai.seihou?lang=en

Professor Yutaka Ie						https://researchmap.jp/read0105668?lang=en

Organic solar cells (OSCs) are attracting attention as a next-generation photovoltaic technology because of their excellent flexibility,
light weight, and designability, as well as the ease of making themlarge-area using a printing process. We recently discovered thatan original molecular unit (FT), in which the fluorene and thiopheneskeletons are perpendicularly linked, is effective in (1) improving
molecular rigidity and (2) suppressing intermolecular π-π stacking. These features are ideal for acceptor materials in OSCs. We
developed an acceptor material TT-FT-DCI using the FT unit andfound that it exhibited high power conversion efficiencies as nonfused acceptor materials. We also developed semi-transparent
OSCs that selectively absorb green-light wavelengths and transmit
red- and blue-wavelengths using FT units (TT-FT-ID). Under pseudo-sunlight transmitted through this photo-active layer, we confirmed that photosynthesis of agricultural crops proceeded.

▍ Background & Results
The photo-active layer of OSCs consists of a mixture of p-type organic semiconductor material (donor) and n-type organic semiconductor material (acceptor). Conventionally, fused ring π-conjugatedskeleton has been considered essential for acceptor materials. However, the construction of fused ring chemical structures generally
requires a multi-step synthesis process. Toward the social implementation of OSCs, non-fused ring acceptor materials, which are easy tosynthesize and easy to develop derivatives, are becoming a focus ofattention. In this background, a three-dimensional molecular unit (FT)with a fluorene skeleton introduced perpendicular to the thiopheneskeleton has been developed through our research on insulated
conductive molecular wires. The FT unit has the effect of improving
the rigidity of the conjugated chain and suppressing intermolecularπ-π stacking, which is consistent with the design guidelines for
acceptor materials for OSCs. An acceptor material TT-FT-DCI, developed using the FT unit, was found to exhibit high power conversion
efficiencies as a non-fused acceptor material.
Recently, we have developed a derivative material TT-FT-ID,
which has selective absorption in the green-light wavelength region. This acceptor material was designed for combination with adonor material P3HT, which also has absorption in the green-lightwavelength region, and the OSC device fabricated by combining these materials functioned as a green wavelength-selective
semi-transparent OSC. Under pseudo-sunlight transmitted throughthis photo-active layer, we confirmed that photosynthesis of agricultural crops proceeded.

also explore innovative organic electronics utilizing the uniquecharacteristics of organic materials.
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Nanotechnologies / Materials

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8+++!!"# $%&'() '!" *!#9+++▍ Significance of the research and Future perspective
In this research, we have developed semi-transparent OSCs
with selective absorption and response in the green-light wavelength region by molecular design of acceptor materials. The newsemi-transparent OSCs were found to be compatible with bothphotovoltaic power generation and crop cultivation. We will investigate the possibilities of this new agrivoltaic technology and will
P a t e n t
Jinnai, Seihou; Saeki, Akinori; Ie, Yutaka et al. Effects of the rigid and sterically bulky structure of non-fused nonfullerene acceptors on transient photon-tocurrent dynamics. Journal of Materials Chemistry A. 2022, 10, 20035-20047. doi: 10.1039/D2TA02604J
Jinnai, Seihou; Washio, Takashi; Ie, Yutaka et al. Green-light wavelength-selective organic solar cells for agrivoltaics: dependence of wavelength on
photosynthetic rate. Faraday Discussions. 2023. doi: 10.1039/D3FD00141E
UR
L https://www.sanken.osaka-u.ac.jp/labs/omm/research-english/
K e y w o r d organic solar cells, organic semiconductors, organic functional materials
Tr e a t i s e