Controlling Molecular Weight of a High Efficiency Donor-Acceptor Conjugated Polymer and Understanding Its Significant Impact on Photovoltaic Properties




The molecular weight (MW) of PBnDT-FTAZ can be precisely controlled by adjusting the stoichiometric ratio of the two monomers, following the Carothers equation. The study of a set of PBnDT-FTAZ polymers with different MWs reveals that the MW significantly influences the morphology and structural order of PBnDTFTAZ in its bulk heterojunction solar cells, with the highest efficiency (over 7%) achieved with the use of a MW of 40 000 g mol−1.