Structural Approach for High Performance Solution-Processed Organic Solar Cells : Acetylene-incorporated Pyrene Derivatives

Abstract

To explore effects of acetylene-incorporation, acetylene-bridged small molecules were successfully synthesized and their photophysical, electrochemical, thermal, and photovoltaic device properties were investigated. The acetylene-incorporation was intended to benefit reduced HOMO-LUMO band gap through extended conjugation, and also the increased ionization potential of the molecules. It is well known that the former is effective in increasing Jsc, while the latter in increasing Voc. Consistent with the expectation and DFT calculation result, acetylene-incorporated pyrene derivatives exhibited planar back-bone, conjugation extension, enhanced light absorption, and low HOMO energy level. Combined with the advanced properties, solution-processed organic solar cells based on a blend of DPP-A-PY(HD) as a donor and [6,6]-phenyl-C71-butyric-acid-methyl-ester (PC70BM) as an acceptor exhibited as high as Voc of 0.85V, Jsc of 8.89 mA cm-2, FF of 41.7% and PCEs of 3.15%.