Improved Charge Transport and Absorption Coefficient in Indacenodithieno[3,2‐b]thiophene‐based Ladder‐Type Polymer Leading to Highly Efficient Polymer Solar Cells

A novel ladder-type donor (IDTT) is developed by substituting the two outward thiophenes of the IDT donor with two thieno[3,2-b]thiophenes. The polymer derived from this donor possesses longer effective conjugation and better planarity, which improves electron delocalization along the polymer backbone and charge mobility. The polymer solar cell device using PIDTT-DFBT shows a high power conversion efficiency of 7.03% with a large open-circuit voltage of 0.95 V without using any additives or post-solvent/thermal annealing processes. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.