Solution processed organic solar cells (OSCs) are promising for future light-harvesting due to their attractive properties of low-cost, flexible and environmental friendly. Though fullerene acceptors have almost dominated OSCs research for the last decades, rapid recent progress have showed great potential for non-fullerene acceptors. The highest efficiency of non-acceptor based OSCs at present use polymer donors and molecular acceptors that contain pricy building blocks and have scalable and labor-intensive problems. Here we report an ADP-based homoleptic zinc(II) complexes Zn(L2)2 as OSC acceptors made from common and inexpensive building blocks and was purified without chromatography columns. The zinc(II) complexe was designed to use in bulk heterojunction OSCs and blended with donor poly(3-hexylthiophene) (P3HT), which is relatively cheap and scalable compared to other high performance polymer donors. Previously, we synthesized a zinc(II) complex of azadipyrromethene (ADP), Zn(WS3)2, which performed well in OSCs when blended with P3HT. Compared to Zn(WS3)2, Zn(L2)2 has four additional hexyl groups on the proximal phenyl rings and the phenyls of the pyrrolic phenylethynyl groups were replaced with the larger aromatic groups, naphthalene.. Incorporation of hexyl groups improves solubility, absorptivity and solid-state ordering of zinc(II) complexes. Zn(L2)2 was tested in OSCs using P3HT as donor and a maximum efficiency of 5.4 % was obtained, which is one of the best efficiencies for P3HT-based OSCs. To understand these results, we are currently analyzing morphology and charge carrier mobility. The high efficiency and easy synthesis of Zn(L2)2 demonstrate that incorporation of solubilizing groups and larger conjugated groups on zinc(II) complexes of ADP is a promising method to develop better ADP- based acceptors.

P3HT-based high-efficiency solar cell using azadipyrromethene-based Zn(II) complexes as electron acceptor

2019 Spring National Meeting

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