Molecular Design and Morphology Control Towards Efficient Polymer Solar Cells Processed using Non-aromatic and Non-chlorinated Solvents

Using an environmentally friendly solvent, N‐methyl‐2‐pyrrolidone, a polymer with benzodithiophene (BDT) and thieno[3,4‐b]thiophene (TT) monomers and triethylene glycol monoether (TEG) side chains, PBDTTT‐TEG, can be processed into an active layer for a polymer solar cell (PSC). Combined with phenyl‐C 71‐butyric acid methyl ester (PC 71 BM) as the acceptor, the resulting PSC has a power conversion efficiency (PCE) of 5.23%. This is the first example of an efficient polymer solar cell fabricated from a non‐aromatic and nonchlorinated solvent.