[6a-A501-1~12] 12.5 Organic solar cells

[6a-A501-3] Syntheses of Low-bandgap Magnesium Porphyrins for Organic Solar Cells

〇Takafumi Nakagwa¹, Keisuke Ogumi², Hiroshi Okada¹, Yutaka Matsuo^1,3 (1.The Univ. of Tokyo, 2.TIRI, 3.USTC)

Keywords:porphyrin derivatives, magnesium, small molecule donor

Porphyrin-based small-molecule electron donors have recently been emerging as a new choice in bulk heterojunction organic solar cells (OSCs). High power conversion efficiencies (PCEs) with these electron-donating materials have been reported in these couple of years because of porphyrins’ strong light absorption efficiency and wide range of absorption extended to near IR region when porphyrin units are conjugated with electron-deficient units such as diketopyrrolopyrrole (DPP). Peng and co-workers recently achieved PCE of 9.06% in 2016 by molecular engineering, examination of additives, and optimization of device fabrication condition. Our group has applied meso-ethynyl-linkages concept to realize maximum conjugation of porphyrins for efficient light absorption and high carrier mobility. With linking porphyrin and aromatic subunits by the ethynyl group, Q-bands of porphyrins becomes intense and red-shifted. Our design has been relying on a tetraethynyl core structure, while other high-performance porphyrin electron donors has been based on bis(ethynyl)porphyrin structures. With the tetraethynyl structure, we anticipate that we can investigate electronic and morphological effect of substituents in the aryl groups on the DPP–porphyrin–DPP chromophore. Another feature of our design is a magnesium metal center.