Effect of self-assembled monolayer treated ZnO as an electron transporting layer on the photovoltaic properties of inverted type polymer solar cells

•The work function ZnO can be tuned by the self assembled monolayer.•SAM treated ZnO used as an electron transporting layer for inverted solar cells.•The direction of interface dipole depends on the dipole orientation of SAM molecules.•The photovoltaic parameters depend on the dipole orientation of SAM molecules.