performance in organic photovoltaic (OPVs) and is one of the major barriers impeding their
commercialization. This work demonstrates that combining the use of a nanoparticle titanium
dioxide (np‐TiO2) electron transporting layer (ETL) and an all‐polymer bulk heterojunction
(BHJ) photoactive layer can endow the derived OPV with a much better water resistivity than
the commonly employed zinc oxide (ZnO) ETL or polymer: small molecule BHJ blends …