有機太陽電池に新たな光明(New light on organic solar cells)

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2022-05-17 スウェーデン・リンショーピング大学

化石燃料を使わないエネルギー供給への移行には、効率的で環境に優しい太陽電池が必要です。リンショーピン大学の研究者らは、これまで不明であった有機太陽電池のエネルギーの流れを明らかにしました。この成果は、より効率的な太陽電池の実現に貢献するもので、『Nature Communications』誌に掲載されました。

<関連情報>

非フラーレン系有機太陽電池のドナー/アクセプター界面におけるエネルギー準位整列のマッピング Mapping the energy level alignment at donor/acceptor interfaces in non-fullerene organic solar cells

Xian’e Li,Qilun Zhang,Jianwei Yu,Ye Xu,Rui Zhang,Chuanfei Wang,Huotian Zhang,Simone Fabiano,Xianjie Liu,Jianhui Hou,Feng Gao & Mats Fahlman
Nature Communications  Published: 19 April 2022
DOI:https://doi.org/10.1038/s41467-022-29702-w

Abstract

Energy level alignment (ELA) at donor (D) -acceptor (A) heterojunctions is essential for understanding the charge generation and recombination process in organic photovoltaic devices. However, the ELA at the D-A interfaces is largely underdetermined, resulting in debates on the fundamental operating mechanisms of high-efficiency non-fullerene organic solar cells. Here, we systematically investigate ELA and its depth-dependent variation of a range of donor/non-fullerene-acceptor interfaces by fabricating and characterizing D-A quasi bilayers and planar bilayers. In contrast to previous assumptions, we observe significant vacuum level (VL) shifts existing at the D-A interfaces, which are demonstrated to be abrupt, extending over only 1–2 layers at the heterojunctions, and are attributed to interface dipoles induced by D-A electrostatic potential differences. The VL shifts result in reduced interfacial energetic offsets and increased charge transfer (CT) state energies which reconcile the conflicting observations of large energy level offsets inferred from neat films and large CT energies of donor – non-fullerene-acceptor systems.

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