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

The authors demonstrate an effective anode interfacial layer based on aqueous solution-processed MoO3 (sMoO(3)) in poly (3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) based bulk-heterojunction organic solar cells (PSCs). Various sMoO(3) concentration (0.03-0.25 wt%) was obtained by dissolving MoO3 powder into deionized water directly with weak solubility. The characteristics of sMoO(3) films evaluated by atomic force microscope (AFM) and scanning electron microscope (SEM) suggest that the sMoO(3) films continuously cover the entire indium tin oxide (ITO) surface. The sMoO(3) based PSCs exhibit comparable power conversion efficiency with poly (3,4-ethylenedioxythiophene)-polysty-renesulfonic acid (PEDOT:PSS) based devices. However, even more importantly, the stability of sMoO(3) based devices have been greatly improved in air under continual light-illumination at 52 mW/cm(2). Further evaluations on Mo valence states and work function of sMoO(3) 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. (C) 2012 Elsevier B. V. All rights reserved.