A star-shaped D-pi-A small molecule based on a tris(2-methoxyphenyl)amine core for highly efficient solution-processed organic solar cells

A new star-shaped D-pi-A small molecule, 2,2',2 ''-{nitrilotris[(3-methoxy-4,1-phenylene)-2,2'-bithiene-5',5-diyleth-1-yl-1-ylidene]}trimalononitrile N(Ph(OMe)-2T-DCN-Me)(3), with high efficiency potential for photovoltaic applications was synthesized. Introducing a soluble tris(2-methoxyphenyl) amine (TPA-MeO) core unit can significantly improve the solubility of star-shaped small molecules without negatively impacting intramolecular conjugation and intermolecular solid state arrangements. Solution-processed organic solar cells based on a blend of N(Ph(OMe)-2T-DCN-Me)(3) and PC70BM show an initially high power conversion efficiency of over 4% under simulated AM 1.5.