A pentacyclic aromatic lactam building block for efficient polymer solar cells

A D–A conjugated polymer (PThTPTI) was developed by using a brand new pentacyclic aromatic lactam acceptor unit (TPTI). PThTPTI possesses good light absorption, thermal stability, and a deep HOMO level. PThTPTI/PC71BM cells afford an outstanding PCE up to 7.80%, with high Voc (0.87 V), Jsc (13.69 mA cm−2) and FF (65.6%), and over 70% EQE in the range of 435–640 nm.