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Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics
Author(s) -
Kong Chen,
Song Byeongseop,
Mueller Emily A.,
Kim Jinsang,
McNeil Anne J.
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201900467
Subject(s) - copolymer , materials science , organic solar cell , polymer solar cell , active layer , chemical engineering , polymer , photovoltaics , side chain , fullerene , polymer chemistry , nanotechnology , photovoltaic system , layer (electronics) , organic chemistry , composite material , chemistry , ecology , engineering , biology , thin film transistor
Recent advances have led to conjugated polymer‐based photovoltaic devices with efficiencies rivaling amorphous silicon. Nevertheless, these devices become less efficient over time due to changes in active layer morphology, thereby hindering their commercialization. Copolymer additives are a promising approach toward stabilizing blend morphologies; however, little is known about the impact of copolymer sequence, composition, and concentration. Herein, the impact of these parameters is determined by synthesizing random, block, and gradient copolymers with a poly(3‐hexylthiophene) (P3HT) backbone and side‐chain fullerenes (phenyl‐C 61 ‐butyric acid methyl ester (PC 61 BM)). These copolymers are evaluated as compatibilizers in photovoltaic devices with P3HT:PC 61 BM as the active layer. The random copolymer with 20 mol% fullerene side chains and at 8 wt% concentration in the blend gives the most stable morphologies. Devices containing the random copolymer also exhibit higher and more stable power conversion efficiencies than the control device. Combined, these studies point to the random copolymer as a promising new scaffold for stabilizing bulk heterojunction photovoltaics.