High Performance All‐Polymer Solar Cell via Polymer Side‐Chain Engineering

An average PCE of 4.2% for all-polymer solar cells from 20 devices with an average J SC of 8.8 mA cm−2 are obtained with a donor-acceptor pair despite a low LUMO-LUMO energy offset of less than 0.1 eV. Incorporation of polystyrene side chains into the donor polymer is found to assist in reducing the phase separation domain length scale, and results in more than 20% enhancement of PCE. We observe a direct correlation between the short circuit...