Aqueous solution-processed MoO3 as an effective interfacial layer in polymer/fullerene based organic solar cells

Abstract

The authors demonstrate an effective anode interfacial layer based on aqueous solution-processed MoO3 (sMoO3) in poly (3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) based bulk-heterojunction organic solar cells (PSCs). Various sMoO3 concentration (0.03–0.25wt%) was obtained by dissolving MoO3 powder into deionized water directly with weak solubility. The characteristics of sMoO3 films evaluated by atomic force microscope (AFM) and scanning electron microscope (SEM) suggest that the sMoO3 films continuously cover the entire indium tin oxide (ITO) surface. The sMoO3 based PSCs exhibit comparable power conversion efficiency with poly (3,4-ethylenedioxythiophene)–polystyrenesulfonic acid (PEDOT:PSS) based devices. However, even more importantly, the stability of sMoO3 based devices have been greatly improved in air under continual light-illumination at 52mW/cm2. Further evaluations on Mo valence states and work function of sMoO3 films by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) demonstrate that the aqueous solution-processed MoO3 could act as an better anode interfacial layer than the conventional PEDOT:PSS.