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Drastic Change of Molecular Orientation in a Thiazolothiazole Copolymer by Molecular‐Weight Control and Blending with PC 61 BM Leads to High Efficiencies in Solar Cells
Author(s) -
Osaka Itaru,
Saito Masahiko,
Mori Hiroki,
Koganezawa Tomoyuki,
Takimiya Kazuo
Publication year - 2012
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201103065
Subject(s) - materials science , polymer solar cell , copolymer , polymer , thiophene , chemical engineering , photovoltaic system , energy conversion efficiency , organic solar cell , polymer chemistry , organic chemistry , optoelectronics , composite material , chemistry , engineering , ecology , biology
A thiazolothiazole–thiophene copolymer is examined as the active material in bulk heterojunction (BHJ) solar cells. By optimizing the molecular weight, the polymer‐based cells exhibit power conversion efficiencies as high as 5.7%. The increase in molecular weight improves the orientational order, and blending with phenyl‐C61‐butyric acid methyl ester (PC 61 BM) changes the orientational motif from edge‐on to face‐on, which accounts for the trend in photovoltaic performances. These results might give new insight into the structure–property relationships in BHJ solar cells.