Naphthalenothiophene imide-based polymer exhibiting over 17% efficiency

With the emergence of highly efficient non-fullerene electron acceptors, there was a demand to develop new efficient polymer donors to match these narrow band-gap molecules. Designing novel electron-deficient monomers that could effectively lower the polymer's HOMO level and fine-tune the polymer's physical properties is vital for polymer donor evolution. Herein, we developed a new monomer naphthalenothiophene imide (NTI) and NTI-based polymer donors—PNTB and PNTB-2T. Polymer chain modification strategy, which works by inserting extra thiophenes, enhanced the efficiency of 3.81% for PNTB:Y6 to 16.72% for the PNTB-2T:Y6 binary device, and eventually enhanced the efficiency to 17.35% for the PNTB-2T:Y6:PCBM ternary device. PNTB-2T-based devices also exhibit excellent batch-to-batch reproducibility in the photovoltaic performance that distinguishes them from other high-performance polymer donors. This work provides new insights into the electron-deficient monomer and high-performance polymer donor renovation of organic solar cells.