Novel Benzodithiophene‐Based Polymer with Intramolecular Non‐Covalent Interactions as a Hole Transporting Layer for Perovskite Solar Cells

Abstract Conjugated polymers represent promising hole‐transport materials (HTM) used for the fabrication of efficient and stable perovskite solar cells (PSCs). Herein, a novel wide‐bandgap polymer Lira24 is designed based on Si( i ‐Pr) 3 ‐substituted benzodithiophene and bis(2‐ethylhexyloxy)benzene moieties. Alternation of selected building blocks in polymer backbone provides the formation of S∙∙∙O non‐covalent intramolecular interactions, which are beneficial for the planarization of polymer chains, better π‐conjugation and consequently improved charge transport. The developed polymeric HTM show enhanced hole mobility of 1.7×10 −3 cm 2 V −1 s −1 in respect to that of widely used PTAA, and well‐aligned energy of highest occupied molecular orbital (−5.39 eV) with valence band of MAPbI 3 absorber material. As a result, PSCs with Lira24 delivered an encouraging power conversion efficiency of 18.1% remarkably outperforming the efficiency of PTAA‐based control devices. The results of this work illustrate the importance of backbone structure control in the design of hole‐transport materials for efficient perovskite photovoltaics.